The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

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Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs. PMID:23593258

The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

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Gang Zhang

Full Text Available Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

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Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

Nap sleep spindle correlates of intelligence.

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Ujma, Péter P; Bódizs, Róbert; Gombos, Ferenc; Stintzing, Johannes; Konrad, Boris N; Genzel, Lisa; Steiger, Axel; Dresler, Martin

2015-11-26

Sleep spindles are thalamocortical oscillations in non-rapid eye movement (NREM) sleep, that play an important role in sleep-related neuroplasticity and offline information processing. Several studies with full-night sleep recordings have reported a positive association between sleep spindles and fluid intelligence scores, however more recently it has been shown that only few sleep spindle measures correlate with intelligence in females, and none in males. Sleep spindle regulation underlies a circadian rhythm, however the association between spindles and intelligence has not been investigated in daytime nap sleep so far. In a sample of 86 healthy male human subjects, we investigated the correlation between fluid intelligence and sleep spindle parameters in an afternoon nap of 100 minutes. Mean sleep spindle length, amplitude and density were computed for each subject and for each derivation for both slow and fast spindles. A positive association was found between intelligence and slow spindle duration, but not any other sleep spindle parameter. As a positive correlation between intelligence and slow sleep spindle duration in full-night polysomnography has only been reported in females but not males, our results suggest that the association between intelligence and sleep spindles is more complex than previously assumed.

Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis

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En-Ju Chou

2016-03-01

Full Text Available CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity.

Sequential activities of Dynein, Mud and Asp in centrosome-spindle coupling maintain centrosome number upon mitosis.

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Bosveld, Floris; Ainslie, Anna; Bellaïche, Yohanns

2017-10-15

Centrosomes nucleate microtubules and are tightly coupled to the bipolar spindle to ensure genome integrity, cell division orientation and centrosome segregation. While the mechanisms of centrosome-dependent microtubule nucleation and bipolar spindle assembly have been the focus of numerous works, less is known about the mechanisms ensuring the centrosome-spindle coupling. The conserved NuMA protein (Mud in Drosophila ) is best known for its role in spindle orientation. Here, we analyzed the role of Mud and two of its interactors, Asp and Dynein, in the regulation of centrosome numbers in Drosophila epithelial cells. We found that Dynein and Mud mainly initiate centrosome-spindle coupling prior to nuclear envelope breakdown (NEB) by promoting correct centrosome positioning or separation, while Asp acts largely independently of Dynein and Mud to maintain centrosome-spindle coupling. Failure in the centrosome-spindle coupling leads to mis-segregation of the two centrosomes into one daughter cell, resulting in cells with supernumerary centrosomes during subsequent divisions. Altogether, we propose that Dynein, Mud and Asp operate sequentially during the cell cycle to ensure efficient centrosome-spindle coupling in mitosis, thereby preventing centrosome mis-segregation to maintain centrosome number. © 2017. Published by The Company of Biologists Ltd.

Semaphorin-Plexin Signaling Controls Mitotic Spindle Orientation during Epithelial Morphogenesis and Repair

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Xia, Jingjing; Swiercz, Jakub M.; Bañón-Rodríguez, Inmaculada

2015-01-01

Morphogenesis, homeostasis, and regeneration of epithelial tissues rely on the accurate orientation of cell divisions, which is specified by the mitotic spindle axis. To remain in the epithelial plane, symmetrically dividing epithelial cells align their mitotic spindle axis with the plane. Here, we...... show that this alignment depends on epithelial cell-cell communication via semaphorin-plexin signaling. During kidney morphogenesis and repair, renal tubular epithelial cells lacking the transmembrane receptor Plexin-B2 or its semaphorin ligands fail to correctly orient the mitotic spindle, leading...... to severe defects in epithelial architecture and function. Analyses of a series of transgenic and knockout mice indicate that Plexin-B2 controls the cell division axis by signaling through its GTPase-activating protein (GAP) domain and Cdc42. Our data uncover semaphorin-plexin signaling as a central...

Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis.

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Chou, En-Ju; Hung, Liang-Yi; Tang, Chieh-Ju C; Hsu, Wen-Bin; Wu, Hsin-Yi; Liao, Pao-Chi; Tang, Tang K

2016-03-29

CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM) dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Accuracy of Spindle Units with Hydrostatic Bearings

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Fedorynenko Dmytro

2016-06-01

Full Text Available The work is devoted to the research of precision regularities in a spindle unit by the trajectory of the spindle installed on hydrostatic bearings. The mathematical model of trajectories spindle with lumped parameters that allows to define the position of the spindle with regard the simultaneous influence of design parameters, geometrical deviations ofform, temperature deformation bearing surfaces, the random nature of operational parameters and technical loads of hydrostatic bearings has been developed. Based on the results of numerical modeling the influence of shape errors of bearing surface of hydrostatic bearing on the statistical characteristics of the radius vector trajectories of the spindle by varying the values rotational speed of the spindle and oil pressure in front hydrostatic bearing has been developed. The obtained statistical regularities of precision spindle unit have been confirmed experimentally. It has been shown that an effective way to increase the precision of spindle units is to regulate the size of the gap in hydrostatic spindle bearings. The new design of an adjustable hydrostatic bearing, which can improve the accuracy of regulation size gap has been proposed.

The Spindle Cell Neoplasms of the Oral Cavity.

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Shamim, Thorakkal

2015-01-01

Spindle cell neoplasms are defined as neoplasms that consist of spindle-shaped cells in the histopathology. Spindle cell neoplasms can affect the oral cavity. In the oral cavity, the origin of the spindle cell neoplasms may be traced to epithelial, mesenchymal and odontogenic components. This article aims to review the spindle cell neoplasms of the oral cavity with emphasis on histopathology.

Stage-independent, single lead EEG sleep spindle detection using the continuous wavelet transform and local weighted smoothing.

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Tsanas, Athanasios; Clifford, Gari D

2015-01-01

Sleep spindles are critical in characterizing sleep and have been associated with cognitive function and pathophysiological assessment. Typically, their detection relies on the subjective and time-consuming visual examination of electroencephalogram (EEG) signal(s) by experts, and has led to large inter-rater variability as a result of poor definition of sleep spindle characteristics. Hitherto, many algorithmic spindle detectors inherently make signal stationarity assumptions (e.g., Fourier transform-based approaches) which are inappropriate for EEG signals, and frequently rely on additional information which may not be readily available in many practical settings (e.g., more than one EEG channels, or prior hypnogram assessment). This study proposes a novel signal processing methodology relying solely on a single EEG channel, and provides objective, accurate means toward probabilistically assessing the presence of sleep spindles in EEG signals. We use the intuitively appealing continuous wavelet transform (CWT) with a Morlet basis function, identifying regions of interest where the power of the CWT coefficients corresponding to the frequencies of spindles (11-16 Hz) is large. The potential for assessing the signal segment as a spindle is refined using local weighted smoothing techniques. We evaluate our findings on two databases: the MASS database comprising 19 healthy controls and the DREAMS sleep spindle database comprising eight participants diagnosed with various sleep pathologies. We demonstrate that we can replicate the experts' sleep spindles assessment accurately in both databases (MASS database: sensitivity: 84%, specificity: 90%, false discovery rate 83%, DREAMS database: sensitivity: 76%, specificity: 92%, false discovery rate: 67%), outperforming six competing automatic sleep spindle detection algorithms in terms of correctly replicating the experts' assessment of detected spindles.

Stage-independent, single lead EEG sleep spindle detection using the continuous wavelet transform and local weighted smoothing

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Athanasios eTsanas

2015-04-01

Full Text Available Sleep spindles are critical in characterizing sleep and have been associated with cognitive function and pathophysiological assessment. Typically, their detection relies on the subjective and time-consuming visual examination of electroencephalogram (EEG signal(s by experts, and has led to large inter-rater variability as a result of poor definition of sleep spindle characteristics. Hitherto, many algorithmic spindle detectors inherently make signal stationarity assumptions (e.g. Fourier transform-based approaches which are inappropriate for EEG signals, and frequently rely on additional information which may not be readily available in many practical settings (e.g. more than one EEG channels, or prior hypnogram assessment. This study proposes a novel signal processing methodology relying solely on a single EEG channel, and provides objective, accurate means towards probabilistically assessing the presence of sleep spindles in EEG signals. We use the intuitively appealing continuous wavelet transform (CWT with a Morlet basis function, identifying regions of interest where the power of the CWT coefficients corresponding to the frequencies of spindles (11-16 Hz is large. The potential for assessing the signal segment as a spindle is refined using local weighted smoothing techniques. We evaluate our findings on two databases: the MASS database comprising 19 healthy controls and the DREAMS sleep spindle database comprising eight participants diagnosed with various sleep pathologies. We demonstrate that we can replicate the experts’ sleep spindles assessment accurately in both databases (MASS database: sensitivity: 84%, specificity: 90%, false discovery rate 83%, DREAMS database: sensitivity: 76%, specificity: 92%, false discovery rate: 67%, outperforming six competing automatic sleep spindle detection algorithms in terms of correctly replicating the experts’ assessment of detected spindles.

Multiple Duties for Spindle Assembly Checkpoint Kinases in Meiosis

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Marston, Adele L.; Wassmann, Katja

2017-01-01

Cell division in mitosis and meiosis is governed by evolutionary highly conserved protein kinases and phosphatases, controlling the timely execution of key events such as nuclear envelope breakdown, spindle assembly, chromosome attachment to the spindle and chromosome segregation, and cell cycle exit. In mitosis, the spindle assembly checkpoint (SAC) controls the proper attachment to and alignment of chromosomes on the spindle. The SAC detects errors and induces a cell cycle arrest in metaphase, preventing chromatid separation. Once all chromosomes are properly attached, the SAC-dependent arrest is relieved and chromatids separate evenly into daughter cells. The signaling cascade leading to checkpoint arrest depends on several protein kinases that are conserved from yeast to man. In meiosis, haploid cells containing new genetic combinations are generated from a diploid cell through two specialized cell divisions. Though apparently less robust, SAC control also exists in meiosis. Recently, it has emerged that SAC kinases have additional roles in executing accurate chromosome segregation during the meiotic divisions. Here, we summarize the main differences between mitotic and meiotic cell divisions, and explain why meiotic divisions pose special challenges for correct chromosome segregation. The less-known meiotic roles of the SAC kinases are described, with a focus on two model systems: yeast and mouse oocytes. The meiotic roles of the canonical checkpoint kinases Bub1, Mps1, the pseudokinase BubR1 (Mad3), and Aurora B and C (Ipl1) will be discussed. Insights into the molecular signaling pathways that bring about the special chromosome segregation pattern during meiosis will help us understand why human oocytes are so frequently aneuploid. PMID:29322045

Multiple Duties for Spindle Assembly Checkpoint Kinases in Meiosis

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Adele L. Marston

2017-12-01

Full Text Available Cell division in mitosis and meiosis is governed by evolutionary highly conserved protein kinases and phosphatases, controlling the timely execution of key events such as nuclear envelope breakdown, spindle assembly, chromosome attachment to the spindle and chromosome segregation, and cell cycle exit. In mitosis, the spindle assembly checkpoint (SAC controls the proper attachment to and alignment of chromosomes on the spindle. The SAC detects errors and induces a cell cycle arrest in metaphase, preventing chromatid separation. Once all chromosomes are properly attached, the SAC-dependent arrest is relieved and chromatids separate evenly into daughter cells. The signaling cascade leading to checkpoint arrest depends on several protein kinases that are conserved from yeast to man. In meiosis, haploid cells containing new genetic combinations are generated from a diploid cell through two specialized cell divisions. Though apparently less robust, SAC control also exists in meiosis. Recently, it has emerged that SAC kinases have additional roles in executing accurate chromosome segregation during the meiotic divisions. Here, we summarize the main differences between mitotic and meiotic cell divisions, and explain why meiotic divisions pose special challenges for correct chromosome segregation. The less-known meiotic roles of the SAC kinases are described, with a focus on two model systems: yeast and mouse oocytes. The meiotic roles of the canonical checkpoint kinases Bub1, Mps1, the pseudokinase BubR1 (Mad3, and Aurora B and C (Ipl1 will be discussed. Insights into the molecular signaling pathways that bring about the special chromosome segregation pattern during meiosis will help us understand why human oocytes are so frequently aneuploid.

Ab initio O(N) elongation-counterpoise method for BSSE-corrected interaction energy analyses in biosystems

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Orimoto, Yuuichi; Xie, Peng; Liu, Kai [Department of Material Sciences, Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-Park, Fukuoka 816-8580 (Japan); Yamamoto, Ryohei [Department of Molecular and Material Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Park, Fukuoka 816-8580 (Japan); Imamura, Akira [Hiroshima Kokusai Gakuin University, 6-20-1 Nakano, Aki-ku, Hiroshima 739-0321 (Japan); Aoki, Yuriko, E-mail: aoki.yuriko.397@m.kyushu-u.ac.jp [Department of Material Sciences, Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-Park, Fukuoka 816-8580 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Hon-chou, Kawaguchi, Saitama 332-0012 (Japan)

2015-03-14

An Elongation-counterpoise (ELG-CP) method was developed for performing accurate and efficient interaction energy analysis and correcting the basis set superposition error (BSSE) in biosystems. The method was achieved by combining our developed ab initio O(N) elongation method with the conventional counterpoise method proposed for solving the BSSE problem. As a test, the ELG-CP method was applied to the analysis of the DNAs’ inter-strands interaction energies with respect to the alkylation-induced base pair mismatch phenomenon that causes a transition from G⋯C to A⋯T. It was found that the ELG-CP method showed high efficiency (nearly linear-scaling) and high accuracy with a negligibly small energy error in the total energy calculations (in the order of 10{sup −7}–10{sup −8} hartree/atom) as compared with the conventional method during the counterpoise treatment. Furthermore, the magnitude of the BSSE was found to be ca. −290 kcal/mol for the calculation of a DNA model with 21 base pairs. This emphasizes the importance of BSSE correction when a limited size basis set is used to study the DNA models and compare small energy differences between them. In this work, we quantitatively estimated the inter-strands interaction energy for each possible step in the transition process from G⋯C to A⋯T by the ELG-CP method. It was found that the base pair replacement in the process only affects the interaction energy for a limited area around the mismatch position with a few adjacent base pairs. From the interaction energy point of view, our results showed that a base pair sliding mechanism possibly occurs after the alkylation of guanine to gain the maximum possible number of hydrogen bonds between the bases. In addition, the steps leading to the A⋯T replacement accompanied with replications were found to be unfavorable processes corresponding to ca. 10 kcal/mol loss in stabilization energy. The present study indicated that the ELG-CP method is promising for

Expanding the histologic spectrum of mucinous tubular and spindle cell carcinoma of the kidney.

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Fine, Samson W; Argani, Pedram; DeMarzo, Angelo M; Delahunt, Brett; Sebo, Thomas J; Reuter, Victor E; Epstein, Jonathan I

2006-12-01

Mucinous tubular and spindle cell carcinomas (MTSCs) are polymorphic neoplasms characterized by small, elongated tubules lined by cuboidal cells and/or cords of spindled cells separated by pale mucinous stroma. Nonclassic morphologic variants and features of MTSC have not been well studied. We identified 17 previously unreported MTSCs from Surgical Pathology and consultative files of the authors and their respective institutions and studied their morphologic features. A total of 10/17 cases were considered "classic," as described above, with 5/10 showing at least focal (20% to 50%) tubular predominance without apparent mucinous matrix. Alcian blue staining revealed abundant (>50%) mucin in all classic cases. Seven of 17 MTSCs were classified as "mucin-poor," with little to no extracellular mucin appreciable by hematoxylin and eosin. Four of these cases showed equal tubular and spindled morphology, 2 cases showed spindle cell predominance (70%; 95%), and 1 case showed tubular predominance (90%). In 5/7 mucin-poor cases, staining for Alcian blue revealed scant (<10%) mucin in cellular areas with the other 2 cases having 30% mucin. Unusual histologic features identified in the 17 cases were: foamy macrophages (n=8), papillations/well formed papillae (n=6/n=1), focal clear cells in tubules (n=3), necrosis (n=3), oncocytic tubules (n=2; 40%, 5%), numerous small vacuoles (n=2), heterotopic bone (n=1), psammomatous calcification (n=1), and nodular growth with lymphocytic cuffing (n=1). An exceptional case contained a well-circumscribed, HMB45-positive angiomyolipoma within the MTSC. MTSCs may be "mucin-poor" and show a marked predominance of either of its principal morphologic components, which coupled with the presence of other unusual features such as clear cells, papillations, foamy macrophages, and necrosis, may mimic other forms of renal cell carcinoma. Pathologists must be aware of the spectrum of histologic findings within MTSCs to ensure their accurate diagnosis.

Measuring mitotic spindle dynamics in budding yeast

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Plumb, Kemp

In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

A defect-driven diagnostic method for machine tool spindles.

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Vogl, Gregory W; Donmez, M Alkan

2015-01-01

Simple vibration-based metrics are, in many cases, insufficient to diagnose machine tool spindle condition. These metrics couple defect-based motion with spindle dynamics; diagnostics should be defect-driven. A new method and spindle condition estimation device (SCED) were developed to acquire data and to separate system dynamics from defect geometry. Based on this method, a spindle condition metric relying only on defect geometry is proposed. Application of the SCED on various milling and turning spindles shows that the new approach is robust for diagnosing the machine tool spindle condition.

Measuring and modeling polymer concentration profiles near spindle boundaries argues that spindle microtubules regulate their own nucleation

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Kaye, Bryan; Stiehl, Olivia; Foster, Peter J.; Shelley, Michael J.; Needleman, Daniel J.; Fürthauer, Sebastian

2018-05-01

Spindles are self-organized microtubule-based structures that segregate chromosomes during cell division. The mass of the spindle is controlled by the balance between microtubule turnover and nucleation. The mechanisms that control the spatial regulation of microtubule nucleation remain poorly understood. While previous work found that microtubule nucleators bind to pre-existing microtubules in the spindle, it is still unclear whether this binding regulates the activity of those nucleators. Here we use a combination of experiments and mathematical modeling to investigate this issue. We measured the concentration of microtubules and soluble tubulin in and around the spindle. We found a very sharp decay in the concentration of microtubules at the spindle interface. This is inconsistent with a model in which the activity of nucleators is independent of their association with microtubules but consistent with a model in which microtubule nucleators are only active when bound to pre-existing microtubules. This argues that the activity of microtubule nucleators is greatly enhanced when bound to pre-existing microtubules. Thus, microtubule nucleators are both localized and activated by the microtubules they generate.

Inscuteable Regulates the Pins-Mud Spindle Orientation Pathway

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Mauser, Jonathon F.; Prehoda, Kenneth E.

2012-01-01

During asymmetric cell division, alignment of the mitotic spindle with the cell polarity axis ensures that the cleavage furrow separates fate determinants into distinct daughter cells. The protein Inscuteable (Insc) is thought to link cell polarity and spindle positioning in diverse systems by binding the polarity protein Bazooka (Baz; aka Par-3) and the spindle orienting protein Partner of Inscuteable (Pins; mPins or LGN in mammals). Here we investigate the mechanism of spindle orientation by the Insc-Pins complex. Previously, we defined two Pins spindle orientation pathways: a complex with Mushroom body defect (Mud; NuMA in mammals) is required for full activity, whereas binding to Discs large (Dlg) is sufficient for partial activity. In the current study, we have examined the role of Inscuteable in mediating downstream Pins-mediated spindle orientation pathways. We find that the Insc-Pins complex requires Gαi for partial activity and that the complex specifically recruits Dlg but not Mud. In vitro competition experiments revealed that Insc and Mud compete for binding to the Pins TPR motifs, while Dlg can form a ternary complex with Insc-Pins. Our results suggest that Insc does not passively couple polarity and spindle orientation but preferentially inhibits the Mud pathway, while allowing the Dlg pathway to remain active. Insc-regulated complex assembly may ensure that the spindle is attached to the cortex (via Dlg) before activation of spindle pulling forces by Dynein/Dynactin (via Mud). PMID:22253744

The Physics of the Metaphase Spindle.

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Oriola, David; Needleman, Daniel J; Brugués, Jan

2018-05-20

The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.

Mitotic spindle proteomics in Chinese hamster ovary cells.

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Mary Kate Bonner

Full Text Available Mitosis is a fundamental process in the development of all organisms. The mitotic spindle guides the cell through mitosis as it mediates the segregation of chromosomes, the orientation of the cleavage furrow, and the progression of cell division. Birth defects and tissue-specific cancers often result from abnormalities in mitotic events. Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology (MudPIT analysis and tandem mass spectrometry. We identified 1155 proteins and used Gene Ontology (GO analysis to categorize proteins into cellular component groups. We then compared our data to the previously published CHO midbody proteome and identified proteins that are unique to the CHO spindle. Our data represent the first mitotic spindle proteome in CHO cells, which augments the list of mitotic spindle components from mammalian cells.

Analysis and topology optimization design of high-speed driving spindle

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Wang, Zhilin; Yang, Hai

2018-04-01

The three-dimensional model of high-speed driving spindle is established by using SOLIDWORKS. The model is imported through the interface of ABAQUS, A finite element analysis model of high-speed driving spindle was established by using spring element to simulate bearing boundary condition. High-speed driving spindle for the static analysis, the spindle of the stress, strain and displacement nephogram, and on the basis of the results of the analysis on spindle for topology optimization, completed the lightweight design of high-speed driving spindle. The design scheme provides guidance for the design of axial parts of similar structures.

Akap350 Recruits Eb1 to The Spindle Poles, Ensuring Proper Spindle Orientation and Lumen Formation in 3d Epithelial Cell Cultures.

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Almada, Evangelina; Tonucci, Facundo M; Hidalgo, Florencia; Ferretti, Anabela; Ibarra, Solange; Pariani, Alejandro; Vena, Rodrigo; Favre, Cristián; Girardini, Javier; Kierbel, Arlinet; Larocca, M Cecilia

2017-11-02

The organization of epithelial cells to form hollow organs with a single lumen requires the accurate three-dimensional arrangement of cell divisions. Mitotic spindle orientation is defined by signaling pathways that provide molecular links between specific spots at the cell cortex and astral microtubules, which have not been fully elucidated. AKAP350 is a centrosomal/Golgi scaffold protein, implicated in the regulation of microtubule dynamics. Using 3D epithelial cell cultures, we found that cells with decreased AKAP350 expression (AKAP350KD) formed polarized cysts with abnormal lumen morphology. Analysis of mitotic cells in AKAP350KD cysts indicated defective spindle alignment. We established that AKAP350 interacts with EB1, a microtubule associated protein that regulates spindle orientation, at the spindle poles. Decrease of AKAP350 expression lead to a significant reduction of EB1 levels at spindle poles and astral microtubules. Conversely, overexpression of EB1 rescued the defective spindle orientation induced by deficient AKAP350 expression. The specific delocalization of the AKAP350/EB1complex from the centrosome decreased EB1 levels at astral microtubules and lead to the formation of 3D-organotypic structures which resembled AKAP350KD cysts. We conclude that AKAP350 recruits EB1 to the spindle poles, ensuring EB1 presence at astral microtubules and proper spindle orientation during epithelial morphogenesis.

Combination spindle-drive system for high precision machining

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Gerth, Howard L.

1977-07-26

A combination spindle-drive is provided for fabrication of optical quality surface finishes. Both the spindle-and-drive utilize the spindle bearings for support, thereby removing the conventional drive-means bearings as a source of vibration. An airbearing spindle is modified to carry at the drive end a highly conductive cup-shaped rotor which is aligned with a stationary stator to produce torque in the cup-shaped rotor through the reaction of eddy currents induced in the rotor. This arrangement eliminates magnetic attraction forces and all force is in the form of torque on the cup-shaped rotor.

Sleep spindles predict stress-related increases in sleep disturbances

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Thien Thanh eDang-Vu

2015-02-01

Full Text Available Background and Aim: Predisposing factors place certain individuals at higher risk for insomnia, especially in the presence of precipitating conditions such as stressful life events. Sleep spindles have been shown to play an important role in the preservation of sleep continuity. Lower spindle density might thus constitute an objective predisposing factor for sleep reactivity to stress. The aim of this study was therefore to evaluate the relationship between baseline sleep spindle density and the prospective change in insomnia symptoms in response to a standardized academic stressor. Methods: 12 healthy students had a polysomnography (PSG recording during a period of lower stress at the beginning of the academic semester, along with an assessment of insomnia complaints using the Insomnia Severity Index (ISI. They completed a second ISI assessment at the end of the semester, a period coinciding with the week prior to final examinations and thus higher stress. Spindle density, amplitude, duration and frequency, as well as sigma power were computed from C4-O2 electroencephalography (EEG derivation during stages N2-N3 of non-rapid-eye-movement (NREM sleep, across the whole night and for each NREM sleep period. To test for the relationship between spindle density and changes in insomnia symptoms in response to academic stress, spindle measurements at baseline were correlated with changes in ISI across the academic semester.Results: Spindle density (as well as spindle amplitude and sigma power, particularly during the first NREM sleep period, negatively correlated with changes in ISI (p < 0.05. Conclusion: Lower spindle activity, especially at the beginning of the night, prospectively predicted larger increases in insomnia symptoms in response to stress. This result indicates that individual differences in sleep spindle activity contribute to the differential vulnerability to sleep disturbances in the face of precipitating factors.

Monitoring Method of Cutting Force by Using Additional Spindle Sensors

Science.gov (United States)

Sarhan, Ahmed Aly Diaa; Matsubara, Atsushi; Sugihara, Motoyuki; Saraie, Hidenori; Ibaraki, Soichi; Kakino, Yoshiaki

This paper describes a monitoring method of cutting forces for end milling process by using displacement sensors. Four eddy-current displacement sensors are installed on the spindle housing of a machining center so that they can detect the radial motion of the rotating spindle. Thermocouples are also attached to the spindle structure in order to examine the thermal effect in the displacement sensing. The change in the spindle stiffness due to the spindle temperature and the speed is investigated as well. Finally, the estimation performance of cutting forces using the spindle displacement sensors is experimentally investigated by machining tests on carbon steel in end milling operations under different cutting conditions. It is found that the monitoring errors are attributable to the thermal displacement of the spindle, the time lag of the sensing system, and the modeling error of the spindle stiffness. It is also shown that the root mean square errors between estimated and measured amplitudes of cutting forces are reduced to be less than 20N with proper selection of the linear stiffness.

Optimal design of high-speed loading spindle based on ABAQUS

Science.gov (United States)

Yang, Xudong; Dong, Yu; Ge, Qingkuan; Yang, Hai

2017-12-01

The three-dimensional model of high-speed loading spindle is established by using ABAQUS’s modeling module. A finite element analysis model of high-speed loading spindle was established by using spring element to simulate bearing boundary condition. The static and dynamic performance of the spindle structure with different specifications of the rectangular spline and the different diameter neck of axle are studied in depth, and the influence of different spindle span on the static and dynamic performance of the high-speed loading spindle is studied. Finally, the optimal structure of the high-speed loading spindle is obtained. The results provide a theoretical basis for improving the overall performance of the test-bed

CENP-W plays a role in maintaining bipolar spindle structure.

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Agnieszka Kaczmarczyk

Full Text Available The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. 'Spindle free' nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction

CENP-W Plays a Role in Maintaining Bipolar Spindle Structure

Science.gov (United States)

Kaczmarczyk, Agnieszka; Sullivan, Kevin F.

2014-01-01

The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. ‘Spindle free’ nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction forces exerted

Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

Science.gov (United States)

Howard, Jonathon; Garzon-Coral, Carlos

2017-11-01

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

Inter-expert and intra-expert reliability in sleep spindle scoring

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Welinder, Peter; Sørensen, Helge Bjarup Dissing

2015-01-01

Objectives To measure the inter-expert and intra-expert agreement in sleep spindle scoring, and to quantify how many experts are needed to build a reliable dataset of sleep spindle scorings. Methods The EEG dataset was comprised of 400 randomly selected 115 s segments of stage 2 sleep from 110...... with higher reliability than the estimation of spindle duration. Reliability of sleep spindle scoring can be improved by using qualitative confidence scores, rather than a dichotomous yes/no scoring system. Conclusions We estimate that 2–3 experts are needed to build a spindle scoring dataset...... with ‘substantial’ reliability (κ: 0.61–0.8), and 4 or more experts are needed to build a dataset with ‘almost perfect’ reliability (κ: 0.81–1). Significance Spindle scoring is a critical part of sleep staging, and spindles are believed to play an important role in development, aging, and diseases of the nervous...

The fission yeast spindle orientation checkpoint: a model that generates tension?

Science.gov (United States)

Gachet, Yannick; Reyes, Céline; Goldstone, Sherilyn; Tournier, Sylvie

2006-10-15

In all eukaryotes, the alignment of the mitotic spindle with the axis of cell polarity is essential for accurate chromosome segregation as well as for the establishment of cell fate, and thus morphogenesis, during development. Studies in invertebrates, higher eukaryotes and yeast suggest that astral microtubules interact with the cell cortex to position the spindle. These microtubules are thought to impose pushing or pulling forces on the spindle poles to affect the rotation or movement of the spindle. In the fission yeast model, where cell division is symmetrical, spindle rotation is dependent on the interaction of astral microtubules with the cortical actin cytoskeleton. In these cells, a bub1-dependent mitotic checkpoint, the spindle orientation checkpoint (SOC), is activated when the spindles fail to align with the cell polarity axis. In this paper we review the mechanism that orientates the spindle during mitosis in fission yeast, and discuss the consequences of misorientation on metaphase progression. Copyright 2006 John Wiley & Sons, Ltd.

Measurement of Spindle Rigidity by using a Magnet Loader

Science.gov (United States)

Yamazaki, Taku; Matsubara, Atsushi; Fujita, Tomoya; Muraki, Toshiyuki; Asano, Kohei; Kawashima, Kazuyuki

The static rigidity of a rotating spindle in the radial direction is investigated in this research. A magnetic loading device (magnet loader) has been developed for the measurement. The magnet loader, which has coils and iron cores, generates the electromagnetic force and attracts a dummy tool attached to the spindle. However, the eddy current is generated in the dummy tool with the spindle rotation and reduces the attractive force at high spindle speed. In order to understand the magnetic flux and eddy current in the dummy tool, the electromagnetic field analysis by FEM was carried out. Grooves on the attraction surface of the dummy tool were designed to cut the eddy current flow. The dimension of the groove were decided based on the FEM analysis, and the designed tool were manufactured and tested. The test result shows that the designed tool successfully reduces the eddy current and recovers the attractive force. By using the magnet loader and the grooved tool, the spindle rigidity can be measured when the spindle rotates with a speed up to 10,000 min-1.

Developmental Changes in Sleep Spindle Characteristics and Sigma Power across Early Childhood

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Ian J. McClain

2016-01-01

Full Text Available Sleep spindles, a prominent feature of the non-rapid eye movement (NREM sleep electroencephalogram (EEG, are linked to cognitive abilities. Early childhood is a time of rapid cognitive and neurophysiological maturation; however, little is known about developmental changes in sleep spindles. In this study, we longitudinally examined trajectories of multiple sleep spindle characteristics (i.e., spindle duration, frequency, integrated spindle amplitude, and density and power in the sigma frequency range (10–16 Hz across ages 2, 3, and 5 years (n=8; 3 males. At each time point, nocturnal sleep EEG was recorded in-home after 13-h of prior wakefulness. Spindle duration, integrated spindle amplitude, and sigma power increased with age across all EEG derivations (C3A2, C4A1, O2A1, and O1A2; all ps < 0.05. We also found a developmental decrease in mean spindle frequency (p<0.05 but no change in spindle density with increasing age. Thus, sleep spindles increased in duration and amplitude but decreased in frequency across early childhood. Our data characterize early developmental changes in sleep spindles, which may advance understanding of thalamocortical brain connectivity and associated lifelong disease processes. These findings also provide unique insights into spindle ontogenesis in early childhood and may help identify electrophysiological features related to healthy and aberrant brain maturation.

Spinal spindle cell haemangioma: an atypical location.

Science.gov (United States)

Talan-Hranilović, J; Vucić, M; Sajko, T; Bedek, D; Tomić, K; Lupret, V

2007-03-01

We present a case of the 31-year-old male patient who complained of weakness in both legs and progressed slowly. Neuroimagine of the thoracic spine showed an intraspinal, extradural mass lesion, measuring 5.3 x 1.2 cm at the Th1-Th3 level. Histologically the lesion was a spindle cell haemangioma composed of dilated vascular spaces and a proliferation of bland appearing interspersed spindle cells. Immunohistochemical analysis was diffusely positive for VIM, SMA and focally for CD34. This lesion is uncommon and shows a predilection for distal extremities. Spindle cell haemangioma within the spine has not been previously reported in the literature.

Sleep spindles during a nap correlate with post sleep memory performance for highly rewarded word-pairs.

Science.gov (United States)

Studte, Sara; Bridger, Emma; Mecklinger, Axel

2017-04-01

The consolidation of new associations is thought to depend in part on physiological processes engaged during non-REM (NREM) sleep, such as slow oscillations and sleep spindles. Moreover, NREM sleep is thought to selectively benefit associations that are adaptive for the future. In line with this, the current study investigated whether different reward cues at encoding are associated with changes in sleep physiology and memory retention. Participants' associative memory was tested after learning a list of arbitrarily paired words both before and after taking a 90-min nap. During learning, word-pairs were preceded by a cue indicating either a high or a low reward for correct memory performance at test. The motivation manipulation successfully impacted retention such that memory declined to a greater extent from pre- to post sleep for low rewarded than for high rewarded word-pairs. In line with previous studies, positive correlations between spindle density during NREM sleep and general memory performance pre- and post-sleep were found. In addition to this, however, a selective positive relationship between memory performance for highly rewarded word-pairs at posttest and spindle density during NREM sleep was also observed. These results support the view that motivationally salient memories are preferentially consolidated and that sleep spindles may be an important underlying mechanism for selective consolidation. Copyright © 2016 Elsevier Inc. All rights reserved.

Local sleep spindle modulations in relation to specific memory cues

NARCIS (Netherlands)

Cox, R.; Hofman, W.F.; de Boer, M.; Talamini, L.M.

2014-01-01

Sleep spindles have been connected to memory processes in various ways. In addition, spindles appear to be modulated at the local cortical network level. We investigated whether cueing specific memories during sleep leads to localized spindle modulations in humans. During learning of word-location

Dual mechanism controls asymmetric spindle position in ascidian germ cell precursors.

Science.gov (United States)

Prodon, François; Chenevert, Janet; Hébras, Céline; Dumollard, Rémi; Faure, Emmanuel; Gonzalez-Garcia, Jose; Nishida, Hiroki; Sardet, Christian; McDougall, Alex

2010-06-01

Mitotic spindle orientation with respect to cortical polarity cues generates molecularly distinct daughter cells during asymmetric cell division (ACD). However, during ACD it remains unknown how the orientation of the mitotic spindle is regulated by cortical polarity cues until furrowing begins. In ascidians, the cortical centrosome-attracting body (CAB) generates three successive unequal cleavages and the asymmetric segregation of 40 localized postplasmic/PEM RNAs in germ cell precursors from the 8-64 cell stage. By combining fast 4D confocal fluorescence imaging with gene-silencing and classical blastomere isolation experiments, we show that spindle repositioning mechanisms are active from prometaphase until anaphase, when furrowing is initiated in B5.2 cells. We show that the vegetal-most spindle pole/centrosome is attracted towards the CAB during prometaphase, causing the spindle to position asymmetrically near the cortex. Next, during anaphase, the opposite spindle pole/centrosome is attracted towards the border with neighbouring B5.1 blastomeres, causing the spindle to rotate (10 degrees /minute) and migrate (3 microm/minute). Dynamic 4D fluorescence imaging of filamentous actin and plasma membrane shows that precise orientation of the cleavage furrow is determined by this second phase of rotational spindle displacement. Furthermore, in pairs of isolated B5.2 blastomeres, the second phase of rotational spindle displacement was lost. Finally, knockdown of PEM1, a protein localized in the CAB and required for unequal cleavage in B5.2 cells, completely randomizes spindle orientation. Together these data show that two separate mechanisms active during mitosis are responsible for spindle positioning, leading to precise orientation of the cleavage furrow during ACD in the cells that give rise to the germ lineage in ascidians.

Modal analysis of spindle of grinder machine based on ANSYS

OpenAIRE

HE Chaocong; LIU Peipei; YAN Chunfei; WANG Muhuan; LIN Jun

2015-01-01

The object of research is to a certain type grinding wheel spindle for which a 3D model of the spindle is established by SolidWorks software and ANSYS software is imported for model analysis.Natural frequency,vibration type and critical speed of the spindle model are obtained and the resulting data are scientifically analyzed.The results show that the spindle structure is reasonable,the machining accuracy can be ensured and the position where the most severe deformation and the main shaft fat...

Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods

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Dorothée Coppieters ’t Wallant

2016-01-01

Full Text Available Sleep spindle is a peculiar oscillatory brain pattern which has been associated with a number of sleep (isolation from exteroceptive stimuli, memory consolidation and individual characteristics (intellectual quotient. Oddly enough, the definition of a spindle is both incomplete and restrictive. In consequence, there is no consensus about how to detect spindles. Visual scoring is cumbersome and user dependent. To analyze spindle activity in a more robust way, automatic sleep spindle detection methods are essential. Various algorithms were developed, depending on individual research interest, which hampers direct comparisons and meta-analyses. In this review, sleep spindle is first defined physically and topographically. From this general description, we tentatively extract the main characteristics to be detected and analyzed. A nonexhaustive list of automatic spindle detection methods is provided along with a description of their main processing principles. Finally, we propose a technique to assess the detection methods in a robust and comparable way.

The Caenorhabditis elegans Elongator complex regulates neuronal alpha-tubulin acetylation.

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Jachen A Solinger

2010-01-01

Full Text Available Although acetylated alpha-tubulin is known to be a marker of stable microtubules in neurons, precise factors that regulate alpha-tubulin acetylation are, to date, largely unknown. Therefore, a genetic screen was employed in the nematode Caenorhabditis elegans that identified the Elongator complex as a possible regulator of alpha-tubulin acetylation. Detailed characterization of mutant animals revealed that the acetyltransferase activity of the Elongator is indeed required for correct acetylation of microtubules and for neuronal development. Moreover, the velocity of vesicles on microtubules was affected by mutations in Elongator. Elongator mutants also displayed defects in neurotransmitter levels. Furthermore, acetylation of alpha-tubulin was shown to act as a novel signal for the fine-tuning of microtubules dynamics by modulating alpha-tubulin turnover, which in turn affected neuronal shape. Given that mutations in the acetyltransferase subunit of the Elongator (Elp3 and in a scaffold subunit (Elp1 have previously been linked to human neurodegenerative diseases, namely Amyotrophic Lateral Sclerosis and Familial Dysautonomia respectively highlights the importance of this work and offers new insights to understand their etiology.

Muscle Spindles and Locomotor Control-An Unrecognized Falls Determinant?

OpenAIRE

Marks Ray

2015-01-01

BACKGROUND: Historically, evidence muscle spindles might be involved in locomotion was provided by their presence in tetrapod antigravity muscles associated with posture and locomotion. Later, Brodal (1962) noted muscle spindles in all muscles of locomotion. To unravel the complexity of the muscle spindle and its role in human locomotor control many investigators have since conducted lesion and/or anaesthesia studies in subhuman species and human contexts. QUESTIONS: How ...

Sleep spindling and fluid intelligence across adolescent development: sex matters

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Róbert eBódizs

2014-11-01

Full Text Available Evidence supports the intricate relationship between sleep electroencephalogram (EEG spindling and cognitive abilities in children and adults. Although sleep EEG changes during adolescence index fundamental brain reorganization, a detailed analysis of sleep spindling and the spindle-intelligence relationship was not yet provided for adolescents. Therefore, adolescent development of sleep spindle oscillations were studied in a home polysomnographic study focusing on the effects of chronological age and developmentally acquired overall mental efficiency (fluid IQ with sex as a potential modulating factor. Subjects were 24 healthy adolescents (12 males with an age range of 15–22 years (mean: 18 years and fluid IQ of 91-126 (mean: 104.12, Raven Progressive Matrices Test. Slow spindles (SSs and fast spindles (FSs were analyzed in 21 EEG derivations by using the individual adjustment method. A significant age-dependent increase in average FS density (r = .57; p = .005 was found. Moreover, fluid IQ correlated with FS density (r = .43; p = .04 and amplitude (r = .41; p = .049. The latter effects were entirely driven by particularly reliable FS-IQ correlations in females [r = .80 (p = .002 and r = .67 (p = .012, for density and amplitude, respectively]. Region-specific analyses revealed that these correlations peak in the fronto-central regions. The control of the age-dependence of FS measures and IQ scores did not considerably reduce the spindle-IQ correlations with respect to FS density. The only positive spindle-index of fluid IQ in males turned out to be the frequency of FSs (r = .60, p = .04. Increases in FS density during adolescence may index reshaped structural connectivity related to white matter maturation in the late developing human brain. The continued development over this age range of cognitive functions is indexed by specific measures of sleep spindling unravelling gender differences in adolescent brain maturation and perhaps cognitive

Thermal Characteristic Analysis and Experimental Study of a Spindle-Bearing System

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Li Wu

2016-07-01

Full Text Available In this paper, a thermo-mechanical coupling analysis model of the spindle-bearing system based on Hertz’s contact theory and a point contact non-Newtonian thermal elastohydrodynamic lubrication (EHL theory are developed. In this model, the effect of preload, centrifugal force, the gyroscopic moment, and the lubrication state of the spindle-bearing system are considered. According to the heat transfer theory, the mathematical model for the temperature field of the spindle system is developed and the effect of the spindle cooling system on the spindle temperature distribution is analyzed. The theoretical simulations and the experimental results indicate that the bearing preload has great effect on the frictional heat generation; the cooling fluid has great effect on the heat balance of the spindle system. If a steady-state heat balance between the friction heat generation and the cooling system cannot be reached, thermally-induced preload will lead to a further increase of the frictional heat generation and then cause the thermal failure of the spindle.

Live imaging of spindle pole disorganization in docetaxel-treated multicolor cells

International Nuclear Information System (INIS)

Sakaushi, Shinji; Nishida, Kumi; Minamikawa, Harumi; Fukada, Takashi; Oka, Shigenori; Sugimoto, Kenji

2007-01-01

Treatment of cells with docetaxel at low concentrations induces aberrant bipolar spindles of which two centrosomes stay at only one pole, and also induces multipolar spindles. To gain insight into the relations between centrosome impairment and structural defects of the spindle, live-cell imaging was performed on a human MDA Auro/imp/H3 cell line in which centrosomes/mitotic spindles, nuclear membrane and chromatin were simultaneously visualized by fluorescent proteins. In the presence of docetaxel at IC 50 concentration, the centrosomes did not segregate, and multiple aster-like structures ectopically arose around the disappearing nuclear membrane. Those ectopic structures formed an acentrosomal pole opposing to the two-centrosomes-containing pole. In late metaphase, one pole often fragmented into multiple spindle poles, leading multipolar division. These results suggest that spindle pole fragility may be induced by centrosome impairment, and collapse of the pole may contribute to induction of aneuploid daughter cells

Role of immunohistochemistry and fluorescence in-situ hybridization (FISH in the diagnosis of spindle and round cell tumors of the kidney

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M. Abbas

2015-09-01

Conclusion: In summary we advise an immunohistochemical panel for round/spindle cell tumors of the kidney and for unclear cases we advise to add (FISH to get the correct diagnosis, as they are completely different regarding surgical approach and post-operative adjuvant therapy.

Magnetic suspension motorized spindle-cutting system dynamics analysis and vibration control review

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Xiaoli QIAO

2016-10-01

Full Text Available The performance of high-speed spindle directly determines the development of high-end machine tools. The cutting system's dynamic characteristics and vibration control effect are inseparable with the performance of the spindle,which influence each other, synergistic effect together the cutting efficiency, the surface quality of the workpiece and tool life in machining process. So, the review status on magnetic suspension motorized spindle, magnetic suspension bearing-flexible rotor system dynamics modeling theory and status of active control technology of flexible magnetic suspension motorized spindle rotor vibration are studied, and the problems which present in the magnetic suspension flexible motorized spindle rotor systems are refined, and the development trend of magnetic levitation motorized spindle and the application prospect is forecasted.

Using Micromanipulation to Analyze Control of Vertebrate Meiotic Spindle Size

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Jun Takagi

2013-10-01

Full Text Available The polymerization/depolymerization dynamics of microtubules (MTs have been reported to contribute to control of the size and shape of spindles, but quantitative analysis of how the size and shape correlate with the amount and density of MTs in the spindle remains incomplete. Here, we measured these parameters using 3D microscopy of meiotic spindles that self-organized in Xenopus egg extracts and presented a simple equation describing the relationship among these parameters. To examine the validity of the equation, we cut the spindle into two fragments along the pole-to-pole axis by micromanipulation techniques that rapidly decrease the amount of MTs. The spheroidal shape spontaneously recovered within 5 min, but the size of each fragment remained small. The equation we obtained quantitatively describes how the spindle size correlates with the amount of MTs while maintaining the shape and the MT density.

Modal analysis of spindle of grinder machine based on ANSYS

Directory of Open Access Journals (Sweden)

HE Chaocong

2015-10-01

Full Text Available The object of research is to a certain type grinding wheel spindle for which a 3D model of the spindle is established by SolidWorks software and ANSYS software is imported for model analysis.Natural frequency,vibration type and critical speed of the spindle model are obtained and the resulting data are scientifically analyzed.The results show that the spindle structure is reasonable,the machining accuracy can be ensured and the position where the most severe deformation and the main shaft fatigue fracture may occur can be found out,which also provide the theoretical basis for further optimization design and precision control.

Parietal Fast Sleep Spindle Density Decrease in Alzheimer's Disease and Amnesic Mild Cognitive Impairment

Science.gov (United States)

Gorgoni, Maurizio; Lauri, Giulia; Truglia, Ilaria; Cordone, Susanna; Sarasso, Simone; Scarpelli, Serena; Mangiaruga, Anastasia; D'Atri, Aurora; Tempesta, Daniela; Ferrara, Michele; Marra, Camillo; Rossini, Paolo Maria; De Gennaro, Luigi

2016-01-01

Several studies have identified two types of sleep spindles: fast (13–15 Hz) centroparietal and slow (11–13 Hz) frontal spindles. Alterations in spindle activity have been observed in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). Only few studies have separately assessed fast and slow spindles in these patients showing a reduction of fast spindle count, but the possible local specificity of this phenomenon and its relation to cognitive decline severity are not clear. Moreover, fast and slow spindle density have never been assessed in AD/MCI. We have assessed fast and slow spindles in 15 AD patients, 15 amnesic MCI patients, and 15 healthy elderly controls (HC). Participants underwent baseline polysomnographic recording (19 cortical derivations). Spindles during nonrapid eye movements sleep were automatically detected, and spindle densities of the three groups were compared in the derivations where fast and slow spindles exhibited their maximum expression (parietal and frontal, resp.). AD and MCI patients showed a significant parietal fast spindle density decrease, positively correlated with Minimental State Examination scores. Our results suggest that AD-related changes in spindle density are specific for frequency and location, are related to cognitive decline severity, and may have an early onset in the pathology development. PMID:27066274

Sleep spindling and fluid intelligence across adolescent development: sex matters.

Science.gov (United States)

Bódizs, Róbert; Gombos, Ferenc; Ujma, Péter P; Kovács, Ilona

2014-01-01

Evidence supports the intricate relationship between sleep electroencephalogram (EEG) spindling and cognitive abilities in children and adults. Although sleep EEG changes during adolescence index fundamental brain reorganization, a detailed analysis of sleep spindling and the spindle-intelligence relationship was not yet provided for adolescents. Therefore, adolescent development of sleep spindle oscillations were studied in a home polysomnographic study focusing on the effects of chronological age and developmentally acquired overall mental efficiency (fluid IQ) with sex as a potential modulating factor. Subjects were 24 healthy adolescents (12 males) with an age range of 15-22 years (mean: 18 years) and fluid IQ of 91-126 (mean: 104.12, Raven Progressive Matrices Test). Slow spindles (SSs) and fast spindles (FSs) were analyzed in 21 EEG derivations by using the individual adjustment method (IAM). A significant age-dependent increase in average FS density (r = 0.57; p = 0.005) was found. Moreover, fluid IQ correlated with FS density (r = 0.43; p = 0.04) and amplitude (r = 0.41; p = 0.049). The latter effects were entirely driven by particularly reliable FS-IQ correlations in females [r = 0.80 (p = 0.002) and r = 0.67 (p = 0.012), for density and amplitude, respectively]. Region-specific analyses revealed that these correlations peak in the fronto-central regions. The control of the age-dependence of FS measures and IQ scores did not considerably reduce the spindle-IQ correlations with respect to FS density. The only positive spindle-index of fluid IQ in males turned out to be the frequency of FSs (r = 0.60, p = 0.04). Increases in FS density during adolescence may index reshaped structural connectivity related to white matter maturation in the late developing human brain. The continued development over this age range of cognitive functions is indexed by specific measures of sleep spindling unraveling gender differences in adolescent brain maturation and perhaps

Hybrid Prediction Model of the Temperature Field of a Motorized Spindle

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Lixiu Zhang

2017-10-01

Full Text Available The thermal characteristics of a motorized spindle are the main determinants of its performance, and influence the machining accuracy of computer numerical control machine tools. It is important to accurately predict the thermal field of a motorized spindle during its operation to improve its thermal characteristics. This paper proposes a model to predict the temperature field of a high-speed and high-precision motorized spindle under different working conditions using a finite element model and test data. The finite element model considers the influence of the parameters of the cooling system and the lubrication system, and that of environmental conditions on the coefficient of heat transfer based on test data for the surface temperature of the motorized spindle. A genetic algorithm is used to optimize the coefficient of heat transfer of the spindle, and its temperature field is predicted using a three-dimensional model that employs this optimal coefficient. A prediction model of the 170MD30 temperature field of the motorized spindle is created and simulation data for the temperature field are compared with the test data. The results show that when the speed of the spindle is 10,000 rpm, the relative mean prediction error is 1.5%, and when its speed is 15,000 rpm, the prediction error is 3.6%. Therefore, the proposed prediction model can predict the temperature field of the motorized spindle with high accuracy.

Characteristics of motorized spindle supported by active magnetic bearings

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Xie Zhenyu

2014-12-01

Full Text Available A motorized spindle supported by active magnetic bearings (AMBs is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

Dynamics Analysis of Unbalanced Motorized Spindles Supported on Ball Bearings

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Junfeng Liu

2016-01-01

Full Text Available This paper presents an improved dynamic model for unbalanced high speed motorized spindles. The proposed model includes a Hertz contact force model which takes into the internal clearance and an unbalanced electromagnetic force model based on the energy of the air magnetic field. The nonlinear characteristic of the model is analysed by Lyapunov stability theory and numerical analysis to study the dynamic properties of the spindle system. Finally, a dynamic operating test is carried out on a DX100A-24000/20-type motorized spindle. The good agreement between the numerical solutions and the experimental data indicates that the proposed model is capable of accurately predicting the dynamic properties of motorized spindles. The influence of the unbalanced magnetic force on the system is studied, and the sensitivities of the system parameters to the critical speed of the system are obtained. These conclusions are useful for the dynamic design of high speed motorized spindles.

Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

Science.gov (United States)

Zheng, Jing-gao; Huo, Tiancheng; Tian, Ning; Chen, Tianyuan; Wang, Chengming; Zhang, Ning; Zhao, Fengying; Lu, Danyu; Chen, Dieyan; Ma, Wanyun; Sun, Jia-lin; Xue, Ping

2013-05-01

The spindle plays a crucial role in normal chromosome alignment and segregation during meiosis and mitosis. Studying spindles in living cells noninvasively is of great value in assisted reproduction technology (ART). Here, we present a novel spindle imaging methodology, full-field optical coherence tomography (FF-OCT). Without any dye labeling and fixation, we demonstrate the first successful application of FF-OCT to noninvasive three-dimensional (3-D) live imaging of the meiotic spindles within the mouse living oocytes at metaphase II as well as the mitotic spindles in the living zygotes at metaphase and telophase. By post-processing of the 3-D dataset obtained with FF-OCT, the important morphological and spatial parameters of the spindles, such as short and long axes, spatial localization, and the angle of meiotic spindle deviation from the first polar body in the oocyte were precisely measured with the spatial resolution of 0.7 μm. Our results reveal the potential of FF-OCT as an imaging tool capable of noninvasive 3-D live morphological analysis for spindles, which might be useful to ART related procedures and many other spindle related studies.

TFG-MET fusion in an infantile spindle cell sarcoma with neural features

NARCIS (Netherlands)

Flucke, U.E.; Noesel, M.M. van; Wijnen, M.; Zhang, L.; Chen, C.L.; Sung, Y.S.; Antonescu, C.R.

2017-01-01

An increasing number of congenital and infantile sarcomas displaying a primitive, monomorphic spindle cell phenotype have been characterized to harbor recurrent gene fusions, including infantile fibrosarcoma and congenital spindle cell rhabdomyosarcoma. Here, we report an unusual spindle cell

Taxifolin enhances andrographolide-induced mitotic arrest and apoptosis in human prostate cancer cells via spindle assembly checkpoint activation.

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Zhong Rong Zhang

Full Text Available Andrographolide (Andro suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC, alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

Taxifolin Enhances Andrographolide-Induced Mitotic Arrest and Apoptosis in Human Prostate Cancer Cells via Spindle Assembly Checkpoint Activation

Science.gov (United States)

Wong, Matthew Man-Kin; Chiu, Sung-Kay; Cheung, Hon-Yeung

2013-01-01

Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC. PMID:23382917

Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit.

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Cheen Fei Chin

2016-07-01

Full Text Available Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS formation at the division site to drive acto-myosin ring (AMR constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit.

Fast and slow spindles during the sleep slow oscillation: disparate coalescence and engagement in memory processing.

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Mölle, Matthias; Bergmann, Til O; Marshall, Lisa; Born, Jan

2011-10-01

Thalamo-cortical spindles driven by the up-state of neocortical slow (memory consolidation during sleep. We examined interactions between SOs and spindles in human slow wave sleep, focusing on the presumed existence of 2 kinds of spindles, i.e., slow frontocortical and fast centro-parietal spindles. Two experiments were performed in healthy humans (24.5 ± 0.9 y) investigating undisturbed sleep (Experiment I) and the effects of prior learning (word paired associates) vs. non-learning (Experiment II) on multichannel EEG recordings during sleep. Only fast spindles (12-15 Hz) were synchronized to the depolarizing SO up-state. Slow spindles (9-12 Hz) occurred preferentially at the transition into the SO down-state, i.e., during waning depolarization. Slow spindles also revealed a higher probability to follow rather than precede fast spindles. For sequences of individual SOs, fast spindle activity was largest for "initial" SOs, whereas SO amplitude and slow spindle activity were largest for succeeding SOs. Prior learning enhanced this pattern. The finding that fast and slow spindles occur at different times of the SO cycle points to disparate generating mechanisms for the 2 kinds of spindles. The reported temporal relationships during SO sequences suggest that fast spindles, driven by the SO up-state feed back to enhance the likelihood of succeeding SOs together with slow spindles. By enforcing such SO-spindle cycles, particularly after prior learning, fast spindles possibly play a key role in sleep-dependent memory processing.

Force encoding in muscle spindles during stretch of passive muscle.

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Kyle P Blum

2017-09-01

Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

Force encoding in muscle spindles during stretch of passive muscle.

Science.gov (United States)

Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

2017-09-01

Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

A New Approach to Spindle Radial Error Evaluation Using a Machine Vision System

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Kavitha C.

2017-03-01

Full Text Available The spindle rotational accuracy is one of the important issues in a machine tool which affects the surface topography and dimensional accuracy of a workpiece. This paper presents a machine-vision-based approach to radial error measurement of a lathe spindle using a CMOS camera and a PC-based image processing system. In the present work, a precisely machined cylindrical master is mounted on the spindle as a datum surface and variations of its position are captured using the camera for evaluating runout of the spindle. The Circular Hough Transform (CHT is used to detect variations of the centre position of the master cylinder during spindle rotation at subpixel level from a sequence of images. Radial error values of the spindle are evaluated using the Fourier series analysis of the centre position of the master cylinder calculated with the least squares curve fitting technique. The experiments have been carried out on a lathe at different operating speeds and the spindle radial error estimation results are presented. The proposed method provides a simpler approach to on-machine estimation of the spindle radial error in machine tools.

Xenopus laevis Kif18A is a highly processive kinesin required for meiotic spindle integrity

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Martin M. Möckel

2017-04-01

Full Text Available The assembly and functionality of the mitotic spindle depends on the coordinated activities of microtubule-associated motor proteins of the dynein and kinesin superfamily. Our current understanding of the function of motor proteins is significantly shaped by studies using Xenopus laevis egg extract as its open structure allows complex experimental manipulations hardly feasible in other model systems. Yet, the Kinesin-8 orthologue of human Kif18A has not been described in Xenopus laevis so far. Here, we report the cloning and characterization of Xenopus laevis (Xl Kif18A. Xenopus Kif18A is expressed during oocyte maturation and its depletion from meiotic egg extract results in severe spindle defects. These defects can be rescued by wild-type Kif18A, but not Kif18A lacking motor activity or the C-terminus. Single-molecule microscopy assays revealed that Xl_Kif18A possesses high processivity, which depends on an additional C-terminal microtubule-binding site. Human tissue culture cells depleted of endogenous Kif18A display mitotic defects, which can be rescued by wild-type, but not tail-less Xl_Kif18A. Thus, Xl_Kif18A is the functional orthologue of human Kif18A whose activity is essential for the correct function of meiotic spindles in Xenopus oocytes.

Automatic Sleep Spindle Detection and Genetic Influence Estimation Using Continuous Wavelet Transform

NARCIS (Netherlands)

Adamczyk, M.; Genzel, L.K.E.; Dresler, M.; Steiger, A.; Friess, E.

2015-01-01

Mounting evidence for the role of sleep spindles in neuroplasticity has led to an increased interest in these non-rapid eye movement (NREM) sleep oscillations. It has been hypothesized that fast and slow spindles might play a different role in memory processing. Here, we present a new sleep spindle

Spindle neurons of the human anterior cingulate cortex

Science.gov (United States)

Nimchinsky, E. A.; Vogt, B. A.; Morrison, J. H.; Hof, P. R.; Bloom, F. E. (Principal Investigator)

1995-01-01

The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer-assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triple was present in a large percentage of these neurons and that they did not contain calcium-binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.

Intercentrosomal angular separation during mitosis plays a crucial role for maintaining spindle stability

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Sutradhar, S.; Basu, S.; Paul, R.

2015-10-01

Cell division through proper spindle formation is one of the key puzzles in cell biology. In most mammalian cells, chromosomes spontaneously arrange to achieve a stable bipolar spindle during metaphase which eventually ensures proper segregation of the DNA into the daughter cells. In this paper, we present a robust three-dimensional mechanistic model to investigate the formation and maintenance of a bipolar mitotic spindle in mammalian cells under different physiological constraints. Using realistic parameters, we test spindle viability by measuring the spindle length and studying the chromosomal configuration. The model strikingly predicts a feature of the spindle instability arising from the insufficient intercentrosomal angular separation and impaired sliding of the interpolar microtubules. In addition, our model successfully reproduces chromosomal patterns observed in mammalian cells, when activity of different motor proteins is perturbed.

Relationship between focal penicillin spikes and cortical spindles in the cerveau isolé cat.

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McLachlan, R S; Kaibara, M; Girvin, J P

1983-01-01

Using the unanesthetized, cerveau isolé preparation in the cat, the association between artificially induced penicillin (PCN) spikes and spontaneously occurring electrocorticographic (ECoG) spindles was investigated. Spikes were elicited by surface application of small pledgets of PCN. After the application of PCN, there was a decrease in spindle amplitude but no change in frequency, duration, or spindle wave frequency in the area of the focus. Examination of the times of occurrence of the spikes and spindles disclosed that in the majority of cases, within a few minutes of the initiation of the foci, there was very high simultaneity, usually 100% between the occurrences of these two events. Examination of the times of occurrence of the spikes within the ECoG spindles failed to disclose any compelling evidence which would favor either the hypothesis that spikes "trigger" spindles or the hypothesis that spindles predispose to focal spikes. Thus, whether spikes trigger spindles, or spikes simply occur in a nonspecific manner during the occurrence of the spindle, or whether it is a combination of both these explanations, must remain an open question on the basis of the data available.

Molecular basis of APC/C regulation by the spindle assembly checkpoint

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Zhang, Ziguo; Yang, Jing; Maslen, Sarah; Skehel, Mark; Barford, David

2016-01-01

In the dividing eukaryotic cell the spindle assembly checkpoint (SAC) ensures each daughter cell inherits an identical set of chromosomes. The SAC coordinates the correct attachment of sister chromatid kinetochores to the mitotic spindle with activation of the anaphase-promoting complex/cyclosome (APC/C), the E3 ubiquitin ligase that initiates chromosome separation. In response to unattached kinetochores, the SAC generates the mitotic checkpoint complex (MCC), a multimeric assembly that inhibits the APC/C, delaying chromosome segregation. Here, using cryo-electron microscopy we determined the near-atomic resolution structure of an APC/C-MCC complex (APC/CMCC). We reveal how degron-like sequences of the MCC subunit BubR1 block degron recognition sites on Cdc20, the APC/C coactivator subunit (Cdc20APC/C) responsible for substrate interactions. BubR1 also obstructs binding of UbcH10 (APC/C’s initiating E2) to repress APC/C ubiquitination activity. Conformational variability of the complex allows for UbcH10 association, and we show from a structure of APC/CMCC in complex with UbcH10 how the Cdc20 subunit intrinsic to the MCC (Cdc20MCC) is ubiquitinated, a process that results in APC/C reactivation when the SAC is silenced. PMID:27509861

Sleep Spindles and Intelligence in Early Childhood--Developmental and Trait-Dependent Aspects

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Ujma, Péter P.; Sándor, Piroska; Szakadát, Sára; Gombos, Ferenc; Bódizs, Róbert

2016-01-01

Sleep spindles act as a powerful marker of individual differences in cognitive ability. Sleep spindle parameters correlate with both age-related changes in cognitive abilities and with the age-independent concept of IQ. While some studies have specifically demonstrated the relationship between sleep spindles and intelligence in young children, our…

Spindle-shaped Microstructures: Potential Models for Planktonic Life Forms on Other Worlds

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Oehler, Dorothy Z.; Walsh, Maud M.; Sugitani, Kenichiro; House, Christopher H.

2014-01-01

Spindle-shaped, organic microstructures ("spindles") are now known from Archean cherts in three localities (Figs. 1-4): The 3 Ga Farrel Quartzite from the Pilbara of Australia [1]; the older, 3.3-3.4 Ga Strelley Pool Formation, also from the Pilbara of Australia [2]; and the 3.4 Ga Kromberg Formation of the Barberton Mountain Land of South Africa [3]. Though the spindles were previously speculated to be pseudofossils or epigenetic organic contaminants, a growing body of data suggests that these structures are bona fide microfossils and further, that they are syngenetic with the Archean cherts in which they occur [1-2, 4-10]. As such, the spindles are among some of the oldest-known organically preserved microfossils on Earth. Moreover, recent delta C-13 study of individual spindles from the Farrel Quartzite (using Secondary Ion Mass Spectrometry [SIMS]) suggests that the spindles may have been planktonic (living in open water), as opposed to benthic (living as bottom dwellers in contact with muds or sediments) [9]. Since most Precambrian microbiotas have been described from benthic, matforming communities, a planktonic lifestyle for the spindles suggests that these structures could represent a segment of the Archean biosphere that is poorly known. Here we synthesize the recent work on the spindles, and we add new observations regarding their geographic distribution, robustness, planktonic habit, and long-lived success. We then discuss their potential evolutionary and astrobiological significance.

Frequency Response Studies using Receptance Coupling Approach in High Speed Spindles

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Shaik, Jakeer Hussain; Ramakotaiah, K.; Srinivas, J.

2018-01-01

In order to assess the stability of high speed machining, estimate the frequency response at the end of tool tip is of great importance. Evaluating dynamic response of several combinations of integrated spindle-tool holder-tool will consume a lot of time. This paper presents coupled field dynamic response at tool tip for the entire integrated spindle tool unit. The spindle unit is assumed to be relying over the front and rear bearings and investigated using the Timoshenko beam theory to arrive the receptances at different locations of the spindle-tool unit. The responses are further validated with conventional finite element model as well as with the experiments. This approach permits quick outputs without losing accuracy of solution and further these methods are utilized to analyze the various design variables on system dynamics. The results obtained through this analysis are needed to design the better spindle unit in an attempt to reduce the frequency amplitudes at the tool tip to improvise the milling stability during cutting process.

Sleep Spindle Detection and Prediction Using a Mixture of Time Series and Chaotic Features

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Amin Hekmatmanesh

2017-01-01

Full Text Available It is well established that sleep spindles (bursts of oscillatory brain electrical activity are significant indicators of learning, memory and some disease states. Therefore, many attempts have been made to detect these hallmark patterns automatically. In this pilot investigation, we paid special attention to nonlinear chaotic features of EEG signals (in combination with linear features to investigate the detection and prediction of sleep spindles. These nonlinear features included: Higuchi's, Katz's and Sevcik's Fractal Dimensions, as well as the Largest Lyapunov Exponent and Kolmogorov's Entropy. It was shown that the intensity map of various nonlinear features derived from the constructive interference of spindle signals could improve the detection of the sleep spindles. It was also observed that the prediction of sleep spindles could be facilitated by means of the analysis of these maps. Two well-known classifiers, namely the Multi-Layer Perceptron (MLP and the K-Nearest Neighbor (KNN were used to distinguish between spindle and non-spindle patterns. The MLP classifier produced a~high discriminative capacity (accuracy = 94.93%, sensitivity = 94.31% and specificity = 95.28% with significant robustness (accuracy ranging from 91.33% to 94.93%, sensitivity varying from 91.20% to 94.31%, and specificity extending from 89.79% to 95.28% in separating spindles from non-spindles. This classifier also generated the best results in predicting sleep spindles based on chaotic features. In addition, the MLP was used to find out the best time window for predicting the sleep spindles, with the experimental results reaching 97.96% accuracy.

Active feedback stabilization of axisymmetric modes in highly elongated tokamak plasmas

International Nuclear Information System (INIS)

Ward, D.J.; Hofmann, F.

1993-07-01

Active feedback stabilization of the vertical instability is studied for highly elongated tokamak plasmas (1≤κ≤3), and evaluated in particular for the TCV configuration. It is shown that the feedback can strongly affect the form of the eigenfunction for these highly elongated equilibria, and this can have detrimental effects on the ability of the feedback system to properly detect and stabilize the plasma. A calculation of the vertical displacement that uses poloidal flux measurements, poloidal magnetic field measurements, and corrections for the vessel eddy currents and active feedback currents was found to be effective even in the cases with the worst deformations of the eigenfunction. We also examine how these deformations affect differently shaped equilibria, and it is seen that the magnitude of the deformation of the eigenfunction is strongly function of the plasma elongation. (author) 15 figs., 13 refs

Drosophila parthenogenesis: A tool to decipher centrosomal vs acentrosomal spindle assembly pathways

International Nuclear Information System (INIS)

Riparbelli, Maria Giovanna; Callaini, Giuliano

2008-01-01

Development of unfertilized eggs in the parthenogenetic strain K23-O-im of Drosophila mercatorum requires the stochastic interactions of self-assembled centrosomes with the female chromatin. In a portion of the unfertilized eggs that do not assemble centrosomes, microtubules organize a bipolar anastral mitotic spindle around the chromatin like the one formed during the first female meiosis, suggesting that similar pathways may be operative. In the cytoplasm of eggs in which centrosomes do form, monastral and biastral spindles are found. Analysis by laser scanning confocal microscopy suggests that these spindles are derived from the stochastic interaction of astral microtubules directly with kinetochore regions or indirectly with kinetochore microtubules. Our findings are consistent with the idea that mitotic spindle assembly requires both acentrosomal and centrosomal pathways, strengthening the hypothesis that astral microtubules can dictate the organization of the spindle by capturing kinetochore microtubules

Direct kinetochore–spindle pole connections are not required for chromosome segregation

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Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B.; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G.; McEwen, Bruce F.; Chen, James K.; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M.

2014-01-01

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes′ kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells. PMID:25023516

Direct kinetochore-spindle pole connections are not required for chromosome segregation.

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Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G; McEwen, Bruce F; Chen, James K; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M; Khodjakov, Alexey

2014-07-21

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes' kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells.

Measurement Research of Motorized Spindle Dynamic Stiffness under High Speed Rotating

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Xiaopeng Wang

2015-01-01

Full Text Available High speed motorized spindle has become a key functional unit of high speed machine tools and effectively promotes the development of machine tool technology. The development of higher speed and more power puts forward the stricter requirement for the performance of motorized spindle, especially the dynamic performance which affects the machining accuracy, reliability, and production efficiency. To overcome the problems of ineffective loading and dynamic performance measurement of motorized spindle, a noncontact electromagnetic loading device is developed. The cutting load can be simulated by using electromagnetic force. A new method of measuring force by force sensors is presented, and the steady and transient loading force could be measured exactly. After the high speed machine spindle is tested, the frequency response curves of the spindle relative to machine table are collected at 0~12000 rpm; then the relationships between stiffness and speeds as well as between damping ratio and speeds are obtained. The result shows that not only the static and dynamic stiffness but also the damping ratio declined with the increase of speed.

Tension-Induced Error Correction and Not Kinetochore Attachment Status Activates the SAC in an Aurora-B/C-Dependent Manner in Oocytes.

Science.gov (United States)

Vallot, Antoine; Leontiou, Ioanna; Cladière, Damien; El Yakoubi, Warif; Bolte, Susanne; Buffin, Eulalie; Wassmann, Katja

2018-01-08

Cell division with partitioning of the genetic material should take place only when paired chromosomes named bivalents (meiosis I) or sister chromatids (mitosis and meiosis II) are correctly attached to the bipolar spindle in a tension-generating manner. For this to happen, the spindle assembly checkpoint (SAC) checks whether unattached kinetochores are present, in which case anaphase onset is delayed to permit further establishment of attachments. Additionally, microtubules are stabilized when they are attached and under tension. In mitosis, attachments not under tension activate the so-named error correction pathway depending on Aurora B kinase substrate phosphorylation. This leads to microtubule detachments, which in turn activates the SAC [1-3]. Meiotic divisions in mammalian oocytes are highly error prone, with severe consequences for fertility and health of the offspring [4, 5]. Correct attachment of chromosomes in meiosis I leads to the generation of stretched bivalents, but-unlike mitosis-not to tension between sister kinetochores, which co-orient. Here, we set out to address whether reduction of tension applied by the spindle on bioriented bivalents activates error correction and, as a consequence, the SAC. Treatment of oocytes in late prometaphase I with Eg5 kinesin inhibitor affects spindle tension, but not attachments, as we show here using an optimized protocol for confocal imaging. After Eg5 inhibition, bivalents are correctly aligned but less stretched, and as a result, Aurora-B/C-dependent error correction with microtubule detachment takes place. This loss of attachments leads to SAC activation. Crucially, SAC activation itself does not require Aurora B/C kinase activity in oocytes. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparison of two sleep spindle detection methods based on all night averages: individually adjusted versus fixed frequencies

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Péter Przemyslaw Ujma

2015-02-01

Full Text Available Sleep spindles are frequently studied for their relationship with state and trait cognitive variables, and they are thought to play an important role in sleep-related memory consolidation. Due to their frequent occurrence in NREM sleep, the detection of sleep spindles is only feasible using automatic algorithms, of which a large number is available. We compared subject averages of the spindle parameters computed by a fixed frequency (11-13 Hz for slow spindles, 13-15 Hz for fast spindles automatic detection algorithm and the individual adjustment method (IAM, which uses individual frequency bands for sleep spindle detection. Fast spindle duration and amplitude are strongly correlated in the two algorithms, but there is little overlap in fast spindle density and slow spindle parameters in general. The agreement between fixed and manually determined sleep spindle frequencies is limited, especially in case of slow spindles. This is the most likely reason for the poor agreement between the two detection methods in case of slow spindle parameters. Our results suggest that while various algorithms may reliably detect fast spindles, a more sophisticated algorithm primed to individual spindle frequencies is necessary for the detection of slow spindles as well as individual variations in the number of spindles in general.

Simplified Dynamic Analysis of Grinders Spindle Node

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Demec, Peter

2014-12-01

The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

Pituitary spindle cell oncocytoma

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Soledad Sosa

2018-01-01

Full Text Available Spindle cell oncocytoma is an infrequent benign non-endocrine sellar neoplasm. Due to its similar morphology to pituitary adenomas, consideration of this differential diagnosis would conduce to a more careful surgical approach in order to avoid intraoperative bleeding and aiming to a complete resection, on which depends long-term outcomes. We present the case of a 60-year-old male who complained about visual abnormalities, with computerized visual field confirmation. On biochemistry, a panhypopituitarism was detected. The brain magnetic resonance images showed a sellar mass. A non-functioning pituitary macroadenoma was presumptively diagnosed and due to the visual impairment, surgical transesphenoidal treatment was indicated. The histological diagnosis was spindle cell oncocytoma. Five months after surgery, the control image demonstrated a lesion that was considered as remnant tumor, hence radiosurgery was performed. During the follow-up, the tumor reduced its size and four years after initial treatment, the sellar resonance imaging showed disappearance of the residual tumor. Communication of new cases of this rare entity will enlarge the existing evidence and will help to determinate the most effective treatment and prognosis.

Sleep Spindles as Biomarker for Early Detection of Neurodegenerative Disorders

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to the use of sleep spindles as a novel biomarker for early diagnosis of synucleinopathies, in particular Parkinson's disease (PD). The method is based on automatic detection of sleep spindles. The method may be combined with measurements of one or more further...

Automatic sleep spindle detection: Benchmarking with fine temporal resolution using open science tools

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Christian eO'Reilly

2015-06-01

Full Text Available Sleep spindle properties index cognitive faculties such as memory consolidation and diseases such as major depression. For this reason, scoring sleep spindle properties in polysomnographic recordings has become an important activity in both research and clinical settings. The tediousness of this manual task has motivated efforts for its automation. Although some progress has been made, increasing the temporal accuracy of spindle scoring and improving the performance assessment methodology are two aspects needing more attention. In this paper, four open-access automated spindle detectors with fine temporal resolution are proposed and tested against expert scoring of two proprietary and two open-access databases. Results highlight several findings: 1 that expert scoring and polysomnographic databases are important confounders when comparing the performance of spindle detectors tested using different databases or scorings; 2 because spindles are sparse events, specificity estimates are potentially misleading for assessing automated detector performance; 3 reporting the performance of spindle detectors exclusively with sensitivity and specificity estimates, as is often seen in the literature, is insufficient; including sensitivity, precision and a more comprehensive statistic such as Matthew’s correlation coefficient, F1-score, or Cohen’s κ is necessary for adequate evaluation; 4 reporting statistics for some reasonable range of decision thresholds provides a much more complete and useful benchmarking; 5 performance differences between tested automated detectors were found to be similar to those between available expert scorings; 6 much more development is needed to effectively compare the performance of spindle detectors developed by different research teams. Finally, this work clarifies a long-standing but only seldom posed question regarding whether expert scoring truly is a reliable gold standard for sleep spindle assessment.

Centrobin-mediated Regulation of the Centrosomal Protein 4.1-associated Protein (CPAP) Level Limits Centriole Length during Elongation Stage*

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Gudi, Radhika; Haycraft, Courtney J.; Bell, P. Darwin; Li, Zihai; Vasu, Chenthamarakshan

2015-01-01

Microtubule-based centrioles in the centrosome mediate accurate bipolar cell division, spindle orientation, and primary cilia formation. Cellular checkpoints ensure that the centrioles duplicate only once in every cell cycle and achieve precise dimensions, dysregulation of which results in genetic instability and neuro- and ciliopathies. The normal cellular level of centrosomal protein 4.1-associated protein (CPAP), achieved by its degradation at mitosis, is considered as one of the major mechanisms that limits centriole growth at a predetermined length. Here we show that CPAP levels and centriole elongation are regulated by centrobin. Exogenous expression of centrobin causes abnormal elongation of centrioles due to massive accumulation of CPAP in the cell. Conversely, CPAP was undetectable in centrobin-depleted cells, suggesting that it undergoes degradation in the absence of centrobin. Only the reintroduction of full-length centrobin, but not its mutant form that lacks the CPAP binding site, could restore cellular CPAP levels in centrobin-depleted cells, indicating that persistence of CPAP requires its interaction with centrobin. Interestingly, inhibition of the proteasome in centrobin-depleted cells restored the cellular and centriolar CPAP expression, suggesting its ubiquitination and proteasome-mediated degradation when centrobin is absent. Intriguingly, however, centrobin-overexpressing cells also showed proteasome-independent accumulation of ubiquitinated CPAP and abnormal, ubiquitin-positive, elongated centrioles. Overall, our results show that centrobin interacts with ubiquitinated CPAP and prevents its degradation for normal centriole elongation function. Therefore, it appears that loss of centrobin expression destabilizes CPAP and triggers its degradation to restrict the centriole length during biogenesis. PMID:25616662

Sleep spindles may predict response to cognitive-behavioral therapy for chronic insomnia.

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Dang-Vu, Thien Thanh; Hatch, Benjamin; Salimi, Ali; Mograss, Melodee; Boucetta, Soufiane; O'Byrne, Jordan; Brandewinder, Marie; Berthomier, Christian; Gouin, Jean-Philippe

2017-11-01

While cognitive-behavioral therapy for insomnia constitutes the first-line treatment for chronic insomnia, only few reports have investigated how sleep architecture relates to response to this treatment. In this pilot study, we aimed to determine whether pre-treatment sleep spindle density predicts treatment response to cognitive-behavioral therapy for insomnia. Twenty-four participants with chronic primary insomnia participated in a 6-week cognitive-behavioral therapy for insomnia performed in groups of 4-6 participants. Treatment response was assessed using the Pittsburgh Sleep Quality Index and the Insomnia Severity Index measured at pre- and post-treatment, and at 3- and 12-months' follow-up assessments. Secondary outcome measures were extracted from sleep diaries over 7 days and overnight polysomnography, obtained at pre- and post-treatment. Spindle density during stage N2-N3 sleep was extracted from polysomnography at pre-treatment. Hierarchical linear modeling analysis assessed whether sleep spindle density predicted response to cognitive-behavioral therapy. After adjusting for age, sex, and education level, lower spindle density at pre-treatment predicted poorer response over the 12-month follow-up, as reflected by a smaller reduction in Pittsburgh Sleep Quality Index over time. Reduced spindle density also predicted lower improvements in sleep diary sleep efficiency and wake after sleep onset immediately after treatment. There were no significant associations between spindle density and changes in the Insomnia Severity Index or polysomnography variables over time. These preliminary results suggest that inter-individual differences in sleep spindle density in insomnia may represent an endogenous biomarker predicting responsiveness to cognitive-behavioral therapy. Insomnia with altered spindle activity might constitute an insomnia subtype characterized by a neurophysiological vulnerability to sleep disruption associated with impaired responsiveness to

Spindle-cell carcinoma of esophagus: a case report

International Nuclear Information System (INIS)

Kim, Ji Chang; Lee, Jae Mun; Jung, Seung Eun; Lee, Kyo Young; Hahn, Seong Tai; Kim, Man Deuk

2001-01-01

Spindle-cell carcinoma of the esophagus is a rare malignant tumor composed of both carcinomatous and sarcomatous elements, and has generated many terminology problems. It is characterized by a bulky polypoid intraluminal mass with a lobulated surface located in the middle third of the esophagus. Local expansion of this organ is observed. The lesion may be pedunculated but despite its bulk, causes little obstruction. We report the imaging findings of a case of spindle-cell carcinoma arising in the upper esophagus

Topographic and sex-related differences in sleep spindles in major depressive disorder: a high-density EEG investigation.

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Plante, D T; Goldstein, M R; Landsness, E C; Peterson, M J; Riedner, B A; Ferrarelli, F; Wanger, T; Guokas, J J; Tononi, G; Benca, R M

2013-03-20

Sleep spindles are believed to mediate several sleep-related functions including maintaining disconnection from the external environment during sleep, cortical development, and sleep-dependent memory consolidation. Prior studies that have examined sleep spindles in major depressive disorder (MDD) have not demonstrated consistent differences relative to control subjects, which may be due to sex-related variation and limited spatial resolution of spindle detection. Thus, this study sought to characterize sleep spindles in MDD using high-density electroencephalography (hdEEG) to examine the topography of sleep spindles across the cortex in MDD, as well as sex-related variation in spindle topography in the disorder. All-night hdEEG recordings were collected in 30 unipolar MDD participants (19 women) and 30 age and sex-matched controls. Topography of sleep spindle density, amplitude, duration, and integrated spindle activity (ISA) were assessed to determine group differences. Spindle parameters were compared between MDD and controls, including analysis stratified by sex. As a group, MDD subjects demonstrated significant increases in frontal and parietal spindle density and ISA compared to controls. When stratified by sex, MDD women demonstrated increases in frontal and parietal spindle density, amplitude, duration, and ISA; whereas MDD men demonstrated either no differences or decreases in spindle parameters. Given the number of male subjects, this study may be underpowered to detect differences in spindle parameters in male MDD participants. This study demonstrates topographic and sex-related differences in sleep spindles in MDD. Further research is warranted to investigate the role of sleep spindles and sex in the pathophysiology of MDD. Copyright © 2012 Elsevier B.V. All rights reserved.

On the Free Vibration Modeling of Spindle Systems: A Calibrated Dynamic Stiffness Matrix

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Omar Gaber

2014-01-01

Full Text Available The effect of bearings on the vibrational behavior of machine tool spindles is investigated. This is done through the development of a calibrated dynamic stiffness matrix (CDSM method, where the bearings flexibility is represented by massless linear spring elements with tuneable stiffness. A dedicated MATLAB code is written to develop and to assemble the element stiffness matrices for the system’s multiple components and to apply the boundary conditions. The developed method is applied to an illustrative example of spindle system. When the spindle bearings are modeled as simply supported boundary conditions, the DSM model results in a fundamental frequency much higher than the system’s nominal value. The simply supported boundary conditions are then replaced by linear spring elements, and the spring constants are adjusted such that the resulting calibrated CDSM model leads to the nominal fundamental frequency of the spindle system. The spindle frequency results are also validated against the experimental data. The proposed method can be effectively applied to predict the vibration characteristics of spindle systems supported by bearings.

Breast spindle cell tumours: about eight cases

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Abd El All Howayda S

2006-07-01

Full Text Available Abstract Background Breast spindle cell tumours (BSCTs, although rare, represent a heterogeneous group with different treatment modalities. This work was undertaken to evaluate the utility of fine needle aspiration cytology (FNAC, histopathology and immunohistochemistry (IHC in differentiating BSCTs. Methods FNAC of eight breast masses diagnosed cytologically as BSCTs was followed by wide excision biopsy. IHC using a panel of antibodies against vimentin, pan-cytokeratin, s100, desmin, smooth muscle actin, CD34, and CD10 was evaluated to define their nature. Results FNAC defined the tumors as benign (n = 4, suspicious (n = 2 and malignant (n = 3, based on the cytopathological criteria of malignancy. Following wide excision biopsy, the tumors were reclassified into benign (n = 5 and malignant (n = 3. In the benign group, the diagnosis was raised histologically and confirmed by IHC for 3 cases (one spindle cell lipoma, one myofibroblastoma and one leiomyoma. For the remaining two cases, the diagnosis was set up after IHC (one fibromatosis and one spindle cell variant of adenomyoepithelioma. In the malignant group, a leiomyosarcoma was diagnosed histologically, while IHC was crucial to set up the diagnosis of one case of spindle cell carcinoma and one malignant myoepithelioma. Conclusion FNAC in BSCTs is an insufficient tool and should be followed by wide excision biopsy. The latter technique differentiate benign from malignant BSCTs and is able in 50% of the cases to set up the definite diagnosis. IHC is of value to define the nature of different benign lesions and is mandatory in the malignant ones for optimal treatment. Awareness of the different types of BSCTs prevents unnecessary extensive therapeutic regimes.

Comparison of a Four-Section Spindle and Stomacher for Efficacy of Detaching Microorganisms from Fresh Vegetables.

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Kim, Do-Kyun; Kim, Soo-Ji; Kang, Dong-Hyun

2015-07-01

This study was undertaken to compare the effect of the spindle and stomacher for detaching microorganisms from fresh vegetables. The spindle is an apparatus for detaching microorganisms from food surfaces, which was developed in our laboratory. When processed with the spindle, food samples were barely disrupted, the original shape was maintained, and the diluent was clear, facilitating further detection analysis more easily than with stomacher treatment. The four-section spindle consists of four sample bag containers (A, B, C, and D) to economize time and effort by simultaneously processing four samples. The aerobic plate counts (APC) of 50 fresh vegetable samples were measured following spindle and stomacher treatment. Correlations between the two methods for each section of the spindle and stomacher were very high (R(2) = 0.9828 [spindle compartment A; Sp A], 0.9855 [Sp B], 0.9848 [Sp C], and 0.9851 [Sp D]). One-tenth milliliter of foodborne pathogens suspensions was inoculated onto surfaces of food samples, and ratios of spindle-to-stomacher enumerations were close to 1.00 log CFU/g between every section of the spindle and stomacher. One of the greatest features of the spindle is that it can treat large-sized samples that exceed 200 g. Uncut whole apples, green peppers, potatoes, and tomatoes were processed by the spindle and by hand massaging by 2 min. Large-sized samples were also assayed for aerobic plate count and recovery of the three foodborne pathogens, and the difference between each section of the spindle and hand massaging was not significant (P > 0.05). This study demonstrated that the spindle apparatus can be an alternative device for detaching microorganisms from all fresh vegetable samples for microbiological analysis by the food processing industry.

Age-related Changes In Sleep Spindles Characteristics During Daytime Recovery Following a 25-Hour Sleep Deprivation

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Thaïna eRosinvil

2015-06-01

Full Text Available Objectives: The mechanisms underlying sleep spindles (~11-15Hz; >0.5s help to protect sleep. With age, it becomes increasingly difficult to maintain sleep at a challenging time (e.g. daytime, even after sleep loss. This study compared spindle characteristics during daytime recovery and nocturnal sleep in young and middle-aged adults. In addition, we explored whether spindles characteristics in baseline nocturnal sleep were associated with the ability to maintain sleep during daytime recovery periods in both age groups.Methods: Twenty-nine young (15 women and 14 men; 27.3 ± 5.0 and 31 middle-aged (19 women and 13 men; 51.6 y ± 5.1 healthy subjects participated in a baseline nocturnal sleep and a daytime recovery sleep after 25 hours of sleep deprivation. Spindles were detected on artefact-free NREM sleep epochs. Spindle density (nb/min, amplitude (μV, frequency (Hz and duration (s were analyzed on parasagittal (linked-ears derivations. Results: In young subjects, spindle frequency increased during daytime recovery sleep as compared to baseline nocturnal sleep in all derivations, whereas middle-aged subjects showed spindle frequency enhancement only in the prefrontal derivation. No other significant interaction between age group and sleep condition was observed. Spindle density for all derivations and centro-occipital spindle amplitude decreased whereas prefrontal spindle amplitude increased from baseline to daytime recovery sleep in both age groups. Finally, no significant correlation was found between spindle characteristics during baseline nocturnal sleep and the marked reduction in sleep efficiency during daytime recovery sleep in both young and middle-aged subjects.Conclusion: These results suggest that the interaction between homeostatic and circadian pressure module spindle frequency differently in aging. Spindle characteristics do not seem to be linked with the ability to maintain daytime recovery sleep.

Vibration sensitivity of human muscle spindles and Golgi tendon organs.

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Fallon, James B; Macefield, Vaughan G

2007-07-01

The responses of the various muscle receptors to vibration are more complicated than a naïve categorization into stretch (muscle spindle primary ending), length (muscle spindle secondary endings), and tension (Golgi tendon organs) receptors. To emphasize the similarity of responses to small length changes, we recorded from 58 individual muscle afferents subserving receptors in the ankle or toe dorsiflexors of awake human subjects (32 primary endings, 20 secondary endings, and six Golgi tendon organs). Transverse sinusoidal vibration was applied to the distal tendon of the receptor-bearing muscle, while subjects either remained completely relaxed or maintained a weak isometric contraction of the appropriate muscle. In relaxed muscle, few units responded in a 1:1 manner to vibration, and there was no evidence of a preferred frequency of activation. In active muscle the response profiles of all three receptor types overlapped, with no significant difference in threshold between receptor types. These results emphasize that when intramuscular tension increases during a voluntary contraction, Golgi tendon organs and muscle spindle secondary endings, not just muscle spindle primary endings, can effectively encode small imposed length changes.

REM sleep behaviour disorder is associated with lower fast and higher slow sleep spindle densities.

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O'Reilly, Christian; Godin, Isabelle; Montplaisir, Jacques; Nielsen, Tore

2015-12-01

To investigate differences in sleep spindle properties and scalp topography between patients with rapid eye movement sleep behaviour disorder (RBD) and healthy controls, whole-night polysomnograms of 35 patients diagnosed with RBD and 35 healthy control subjects matched for age and sex were compared. Recordings included a 19-lead 10-20 electroencephalogram montage and standard electromyogram, electrooculogram, electrocardiogram and respiratory leads. Sleep spindles were automatically detected using a standard algorithm, and their characteristics (amplitude, duration, density, frequency and frequency slope) compared between groups. Topological analyses of group-discriminative features were conducted. Sleep spindles occurred at a significantly (e.g. t34 = -4.49; P = 0.00008 for C3) lower density (spindles ∙ min(-1) ) for RBD (mean ± SD: 1.61 ± 0.56 for C3) than for control (2.19 ± 0.61 for C3) participants. However, when distinguishing slow and fast spindles using thresholds individually adapted to the electroencephalogram spectrum of each participant, densities smaller (31-96%) for fast but larger (20-120%) for slow spindles were observed in RBD in all derivations. Maximal differences were in more posterior regions for slow spindles, but over the entire scalp for fast spindles. Results suggest that the density of sleep spindles is altered in patients with RBD and should therefore be investigated as a potential marker of future neurodegeneration in these patients. © 2015 European Sleep Research Society.

Expert and crowd-sourced validation of an individualized sleep spindle detection method employing complex demodulation and individualized normalization

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Laura eRay

2015-09-01

Full Text Available A spindle detection method was developed that: 1 extracts the signal of interest (i.e., spindle-related phasic changes in sigma relative to ongoing background sigma activity using complex demodulation, 2 accounts for variations of spindle characteristics across the night, scalp derivations and between individuals, and 3 employs a minimum number of sometimes arbitrary, user-defined parameters. Complex demodulation was used to extract instantaneous power in the spindle band. To account for intra- and inter-individual differences, the signal was z-score transformed using a 60s sliding window, per channel, over the course of the recording. Spindle events were detected with a z-score threshold corresponding to a low probability (e.g., 99th percentile. Spindle characteristics, such as amplitude, duration and oscillatory frequency, were derived for each individual spindle following detection, which permits spindles to be subsequently and flexibly categorized as slow or fast spindles from a single detection pass. Spindles were automatically detected in 15 young healthy subjects. Two experts manually identified spindles from C3 during Stage 2 sleep, from each recording; one employing conventional guidelines, and the other, identifying spindles with the aid of a sigma (11-16 Hz filtered channel. These spindles were then compared between raters and to the automated detection to identify the presence of true positives, true negatives, false positives and false negatives. This method of automated spindle detection resolves or avoids many of the limitations that complicate automated spindle detection, and performs well compared to a group of non-experts, and importantly, has good external validity with respect to the extant literature in terms of the characteristics of automatically detected spindles.

Spindle formation in the mouse embryo requires Plk4 in the absence of centrioles.

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Coelho, Paula A; Bury, Leah; Sharif, Bedra; Riparbelli, Maria G; Fu, Jingyan; Callaini, Giuliano; Glover, David M; Zernicka-Goetz, Magdalena

2013-12-09

During the first five rounds of cell division in the mouse embryo, spindles assemble in the absence of centrioles. Spindle formation initiates around chromosomes, but the microtubule nucleating process remains unclear. Here we demonstrate that Plk4, a protein kinase known as a master regulator of centriole formation, is also essential for spindle assembly in the absence of centrioles. Depletion of maternal Plk4 prevents nucleation and growth of microtubules and results in monopolar spindle formation. This leads to cytokinesis failure and, consequently, developmental arrest. We show that Plk4 function depends on its kinase activity and its partner protein, Cep152. Moreover, tethering Cep152 to cellular membranes sequesters Plk4 and is sufficient to trigger spindle assembly from ectopic membranous sites. Thus, the Plk4-Cep152 complex has an unexpected role in promoting microtubule nucleation in the vicinity of chromosomes to mediate bipolar spindle formation in the absence of centrioles. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Different maturational changes of fast and slow sleep spindles in the first four years of life.

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D'Atri, Aurora; Novelli, Luana; Ferrara, Michele; Bruni, Oliviero; De Gennaro, Luigi

2018-02-01

Massive changes in brain morphology and function in the first years of life reveal a postero-anterior trajectory of cortical maturation accompanied by regional modifications of NREM sleep. One of the most sensible marker of this maturation process is represented by electroencephalographic (EEG) activity within the frequency range of sleep spindles. However, direct evidence that these changes actually reflect maturational modifications of fast and slow spindles still lacks. Our study aimed at answering the following questions: 1. Do cortical changes at 11.50 Hz frequency correspond to slow spindles? 2. Do fast and slow spindles show different age trajectories and different topographical distributions? 3. Do changes in peak frequency explain age changes of slow and fast spindles? We measured the antero-posterior changes of slow and fast spindles in the first 60 min of nightly sleep of 39 infants and children (0-48 mo.). We found that (A) changes of slow spindles from birth to childhood mostly affect frontal areas (B) variations of fast and slow spindles across age groups go in opposite direction, the latter progressively increasing across ages; (C) this process is not merely reducible to changes of spindle frequency. As a main finding, our cross-sectional study shows that the first form of mature spindle (i.e., corresponding to the adult phasic event of NREM sleep) is marked by the emergence of slow spindles on anterior regions around the age of 12 months. Copyright © 2017 Elsevier B.V. All rights reserved.

Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder

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Nishida M

2016-01-01

Full Text Available Masaki Nishida,1 Yusaku Nakashima,2 Toru Nishikawa11Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, 2Medical Technology Research Laboratory, Research and Development Division, Medical Business Unit, Sony Corporation, Tokyo, JapanIntroduction: Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process.Methods: Healthy control participants (n=17 and patients medicated for major depressive disorder (n=11 were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement. Participants' brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs. Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5–16 Hz and slow-frequency spindle activity (10.5–12.5 Hz.Result: Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups.Conclusion: Because the changes in slow

Influence of the number of elongated fiducial markers on the localization accuracy of the prostate

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de Boer, Johan; de Bois, Josien; van Herk, Marcel; Sonke, Jan-Jakob

2012-10-01

Implanting fiducial markers for localization purposes has become an accepted practice in radiotherapy for prostate cancer. While many correction strategies correct for translations only, advanced correction protocols also require knowledge of the rotation of the prostate. For this purpose, typically, three or more markers are implanted. Elongated fiducial markers provide more information about their orientation than traditional round or cylindrical markers. Potentially, fewer markers are required. In this study, we evaluate the effect of the number of elongated markers on the localization accuracy of the prostate. To quantify the localization error, we developed a model that estimates, at arbitrary locations in the prostate, the registration error caused by translational and rotational uncertainties of the marker registration. Every combination of one, two and three markers was analysed for a group of 24 patients. The average registration errors at the prostate surface were 0.3-0.8 mm and 0.4-1 mm for registrations on, respectively, three markers and two markers located on different sides of the prostate. Substantial registration errors (2.0-2.2 mm) occurred at the prostate surface contralateral to the markers when two markers were implanted on the same side of the prostate or only one marker was used. In conclusion, there is no benefit in using three elongated markers: two markers accurately localize the prostate if they are implanted at some distance from each other.

Valve spindle gland

International Nuclear Information System (INIS)

Burda, Z.; Harazim, A.; Kerlin, K.

1979-01-01

A gland is proposed of the valve spindle designed for radioactive or otherwise harmful media, such as in nuclear power plant primary circuits. The gland is installed in the valve cover and consists of a primary and a secondary part and of a gland case partitioning the gland space into two chambers. The bottom face of the gland case is provided with a double-sided collar for controlling the elements of the bottom primary gland while the top face is provided with a removable flange. (M.S.)

On the Dynamics of Rocking Motion of the Hard-Disk Drive Spindle Motor System

Science.gov (United States)

Wang, Joseph

Excessive rocking motion of the spindle motor system can cause track misregistration resulting in poor throughput or even drive failure. The chance of excessive disk stack rocking increases as a result of decreasing torsional stiffness of spindle motor bearing system due to the market demand for low profile hard drives. As the track density increases and the vibration specification becomes increasingly stringent, rocking motion of a spindle motor system deserves even more attention and has become a primary challenge for a spindle motor system designer. Lack of understanding of the rocking phenomenon combined with misleading paradox has presented a great difficulty in the effort of avoiding the rocking motion in the hard-disk drive industry. This paper aims to provide fundamental understanding of the rocking phenomenon of a rotating spindle motor system, to clarify the paradox in disk-drive industry and to provide a design guide to an optimized spindle system. This paper, theoretically and experimentally, covers a few important areas of industrial interest including the prediction of rocking natural frequencies and mode shape of a rotating spindle, free vibration, and frequency response under common forcing functions such as rotating and fixed-plane forcing functions. The theory presented here meets with agreeable experimental observation.

Status of the tube elongation problem as of June 1976

International Nuclear Information System (INIS)

Alexander, W.K.

1976-01-01

It was discovered in May of 1971 that the N Reactor process tubes had apparently increased in length by as much as one inch. Preliminary observations and measurements led to the tentative conclusion that this observed elongation was linear with accumulated tube exposure and also that it was related in some manner to the tube fabrication process. It appeared that the observed elongation was approximately proportional to the degree of cold work retained in the finished tubes. This latter conclusion was based on the observation that those tubes with approximately 17-18 percent cold work had elongated only about half as much as the standard 30-percent-cold-worked tubes. It was immediately recognized that if such elongation was to continue unchecked it could pose a limit to reactor life since total possible tube expansion, from all causes, is limited to 1.75 inches by nozzle design considerations as shown in Figure 1. Thermal and hydraulic expansion were calculated to total approximately 0.75 inches which left only one inch available to accommodate tube growth or creep. Since discovery of this phenomenon, an extensive measurements program has been carried out to evaluate the extent and rate of tube elongation. Two corrective approaches have been developed and a small number of tubes were modified by each method during the 1976 summer outage. During the 1974, 1975 and 1976 Summer Outages, measurements were made on all tubes to determine the clearance remaining between the nozzle keys and the gas packing ring. These readings not only give an overall picture of the extent of elongation, but also provide immediate data indicating which tubes are about out of clearance. The report presents an evaluation of the measurements taken to date

In-silico modeling of the mitotic spindle assembly checkpoint.

Directory of Open Access Journals (Sweden)

Bashar Ibrahim

2008-02-01

Full Text Available The Mitotic Spindle Assembly Checkpoint ((MSAC is an evolutionary conserved mechanism that ensures the correct segregation of chromosomes by restraining cell cycle progression from entering anaphase until all chromosomes have made proper bipolar attachments to the mitotic spindle. Its malfunction can lead to cancer.We have constructed and validated for the human (MSAC mechanism an in silico dynamical model, integrating 11 proteins and complexes. The model incorporates the perspectives of three central control pathways, namely Mad1/Mad2 induced Cdc20 sequestering based on the Template Model, MCC formation, and APC inhibition. Originating from the biochemical reactions for the underlying molecular processes, non-linear ordinary differential equations for the concentrations of 11 proteins and complexes of the (MSAC are derived. Most of the kinetic constants are taken from literature, the remaining four unknown parameters are derived by an evolutionary optimization procedure for an objective function describing the dynamics of the APC:Cdc20 complex. MCC:APC dissociation is described by two alternatives, namely the "Dissociation" and the "Convey" model variants. The attachment of the kinetochore to microtubuli is simulated by a switching parameter silencing those reactions which are stopped by the attachment. For both, the Dissociation and the Convey variants, we compare two different scenarios concerning the microtubule attachment dependent control of the dissociation reaction. Our model is validated by simulation of ten perturbation experiments.Only in the controlled case, our models show (MSAC behaviour at meta- to anaphase transition in agreement with experimental observations. Our simulations revealed that for (MSAC activation, Cdc20 is not fully sequestered; instead APC is inhibited by MCC binding.

Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast

Science.gov (United States)

Gergely, Zachary R.; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Betterton, Meredith D.

2016-01-01

Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin-8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional, unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we studied the effects of deletion of the fission yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8–deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8–induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen. PMID:27146110

Adaptive Spindle Balancing Using Magnetically Levitated Bearings

International Nuclear Information System (INIS)

BARNEY, PATRICK S.; LAUFFER, JAMES P.; PETTEYS, REBECCA; REDMOND, JAMES M.; SULLIVAN, WILLIAM N.

1999-01-01

A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools, The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller

Afferent Innervation, Muscle Spindles, and Contractures Following Neonatal Brachial Plexus Injury in a Mouse Model.

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Nikolaou, Sia; Hu, Liangjun; Cornwall, Roger

2015-10-01

We used an established mouse model of elbow flexion contracture after neonatal brachial plexus injury (NBPI) to test the hypothesis that preservation of afferent innervation protects against contractures and is associated with preservation of muscle spindles and ErbB signaling. A model of preganglionic C5 through C7 NBPI was first tested in mice with fluorescent axons using confocal imaging to confirm preserved afferent innervation of spindles despite motor end plate denervation. Preganglionic and postganglionic injuries were then created in wild-type mice. Four weeks later, we assessed total and afferent denervation of the elbow flexors by musculocutaneous nerve immunohistochemistry. Biceps muscle volume and cross-sectional area were measured by micro computed tomography. An observer who was blinded to the study protocol measured elbow flexion contractures. Biceps spindle and muscle fiber morphology and ErbB signaling pathway activity were assessed histologically and immunohistochemically. Preganglionic and postganglionic injuries caused similar total denervation and biceps muscle atrophy. However, after preganglionic injuries, afferent innervation was partially preserved and elbow flexion contractures were significantly less severe. Spindles degenerated after postganglionic injury but were preserved after preganglionic injury. ErbB signaling was inactivated in denervated spindles after postganglionic injury but ErbB signaling activity was preserved in spindles after preganglionic injury with retained afferent innervation. Preganglionic and postganglionic injuries were associated with upregulation of ErbB signaling in extrafusal muscle fibers. Contractures after NBPI are associated with muscle spindle degeneration and loss of spindle ErbB signaling activity. Preservation of afferent innervation maintained spindle development and ErbB signaling activity, and protected against contractures. Pharmacologic modulation of ErbB signaling, which is being investigated as a

Sleep Spindle Characteristics in Children with Neurodevelopmental Disorders and Their Relation to Cognition

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Wise, Merrill S.

2016-01-01

Empirical evidence indicates that sleep spindles facilitate neuroplasticity and “off-line” processing during sleep, which supports learning, memory consolidation, and intellectual performance. Children with neurodevelopmental disorders (NDDs) exhibit characteristics that may increase both the risk for and vulnerability to abnormal spindle generation. Despite the high prevalence of sleep problems and cognitive deficits in children with NDD, only a few studies have examined the putative association between spindle characteristics and cognitive function. This paper reviews the literature regarding sleep spindle characteristics in children with NDD and their relation to cognition in light of what is known in typically developing children and based on the available evidence regarding children with NDD. We integrate available data, identify gaps in understanding, and recommend future research directions. Collectively, studies are limited by small sample sizes, heterogeneous populations with multiple comorbidities, and nonstandardized methods for collecting and analyzing findings. These limitations notwithstanding, the evidence suggests that future studies should examine associations between sleep spindle characteristics and cognitive function in children with and without NDD, and preliminary findings raise the intriguing question of whether enhancement or manipulation of sleep spindles could improve sleep-dependent memory and other aspects of cognitive function in this population. PMID:27478646

Spindle Cell Carcinoma of the hypopharynx: a case report

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Dillu Ram Kandel

2018-03-01

Full Text Available Spindle cell carcinoma of hpopharynx is a rare pathology. It is a poorly differentiated variant of squamous cell carcinoma and morphologically resembles sarcoma. This is a disease of old age. It is usually associated with smoking and alcohol abuse. When it is associated with radiation exposure history it behaves more aggressively. Surgery is considered as the main modality of treatment and adjuvant radiotherapy if necessary. Here we present a case of 79 year old male with spindle cell carcinomaof right piriform fossa with 2-month history of progressive dysphasia and hoarseness that has been affecting his ability to speak and swallow with history of weight loss and past history of radiotherapy. So possibility of spindle cell carcinoma of the hypopharynx should beconsidered in an old patient with rapidly developing swelling of the hypopharynx with past history of radiation exposure. As it is a highly aggressive disease it should be treated timely and more aggressively to prolong the survival of the patient.   

Mounting arrangement for the drive system of an air-bearing spindle on a machine tool

Science.gov (United States)

Lunsford, J.S.; Crisp, D.W.; Petrowski, P.L.

1987-12-07

The present invention is directed to a mounting arrangement for the drive system of an air-bearing spindle utilized on a machine tool such as a lathe. The mounting arrangement of the present invention comprises a housing which is secured to the casing of the air bearing in such a manner that the housing position can be selectively adjusted to provide alignment of the air-bearing drive shaft supported by the housing and the air-bearing spindle. Once this alignment is achieved the air between spindle and the drive arrangement is maintained in permanent alignment so as to overcome misalignment problems encountered in the operation of the machine tool between the air-bearing spindle and the shaft utilized for driving the air-bearing spindle.

The spindle assembly checkpoint: More than just keeping track of the spindle.

OpenAIRE

Lawrence, KS; Engebrecht, J

2015-01-01

Genome stability is essential for cell proliferation and survival. Consequently, genome integrity is monitored by two major checkpoints, the DNA damage response (DDR) and the spindle assembly checkpoint (SAC). The DDR monitors DNA lesions in G1, S, and G2 stages of the cell cycle and the SAC ensures proper chromosome segregation in M phase. There have been extensive studies characterizing the roles of these checkpoints in response to the processes for which they are named; however, emerging e...

Influence of the number of elongated fiducial markers on the localization accuracy of the prostate

International Nuclear Information System (INIS)

De Boer, Johan; De Bois, Josien; Van Herk, Marcel; Sonke, Jan-Jakob

2012-01-01

Implanting fiducial markers for localization purposes has become an accepted practice in radiotherapy for prostate cancer. While many correction strategies correct for translations only, advanced correction protocols also require knowledge of the rotation of the prostate. For this purpose, typically, three or more markers are implanted. Elongated fiducial markers provide more information about their orientation than traditional round or cylindrical markers. Potentially, fewer markers are required. In this study, we evaluate the effect of the number of elongated markers on the localization accuracy of the prostate. To quantify the localization error, we developed a model that estimates, at arbitrary locations in the prostate, the registration error caused by translational and rotational uncertainties of the marker registration. Every combination of one, two and three markers was analysed for a group of 24 patients. The average registration errors at the prostate surface were 0.3–0.8 mm and 0.4–1 mm for registrations on, respectively, three markers and two markers located on different sides of the prostate. Substantial registration errors (2.0–2.2 mm) occurred at the prostate surface contralateral to the markers when two markers were implanted on the same side of the prostate or only one marker was used. In conclusion, there is no benefit in using three elongated markers: two markers accurately localize the prostate if they are implanted at some distance from each other. (paper)

Evaluating and Improving Automatic Sleep Spindle Detection by Using Multi-Objective Evolutionary Algorithms

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Min-Yin Liu

2017-05-01

Full Text Available Sleep spindles are brief bursts of brain activity in the sigma frequency range (11–16 Hz measured by electroencephalography (EEG mostly during non-rapid eye movement (NREM stage 2 sleep. These oscillations are of great biological and clinical interests because they potentially play an important role in identifying and characterizing the processes of various neurological disorders. Conventionally, sleep spindles are identified by expert sleep clinicians via visual inspection of EEG signals. The process is laborious and the results are inconsistent among different experts. To resolve the problem, numerous computerized methods have been developed to automate the process of sleep spindle identification. Still, the performance of these automated sleep spindle detection methods varies inconsistently from study to study. There are two reasons: (1 the lack of common benchmark databases, and (2 the lack of commonly accepted evaluation metrics. In this study, we focus on tackling the second problem by proposing to evaluate the performance of a spindle detector in a multi-objective optimization context and hypothesize that using the resultant Pareto fronts for deriving evaluation metrics will improve automatic sleep spindle detection. We use a popular multi-objective evolutionary algorithm (MOEA, the Strength Pareto Evolutionary Algorithm (SPEA2, to optimize six existing frequency-based sleep spindle detection algorithms. They include three Fourier, one continuous wavelet transform (CWT, and two Hilbert-Huang transform (HHT based algorithms. We also explore three hybrid approaches. Trained and tested on open-access DREAMS and MASS databases, two new hybrid methods of combining Fourier with HHT algorithms show significant performance improvement with F1-scores of 0.726–0.737.

Experimental study on bearing preload optimum of machine tool spindle

International Nuclear Information System (INIS)

Xu Tao; Xu Guanghua; Zhang Qin; Hua Cheng; Zhang Hu; Jiang Kuosheng

2012-01-01

An experimental study is conducted to investigate the possibility and the effect of temperature rise and vibration level of bearing by adjusting axial preloads and radial loads in spindle bearing test rig. The shaft of the test rig is driven by a motorized high speed spindle at the range of 0∼20000 rpm. The axial preloads and radial loads on bearings are controlled by using hydraulic pressure which can be adjusted automatically. Temperature rise and radial vibration of test bearings are measured by thermocouples and Polytec portable laser vibrometer PDV100. Experiment shows that the temperature rise of bearings is nonlinear varying with the increase of radial loads, but temperature rise almost increases linearly with the increase of axial preload and rotating speed. In this paper, an alternate axial preload is used for bearings. When the rotating speed passes through the critical speed of the shaft, axial preload of bearings will have a remarkable effect. The low preload could reduce bearing vibration and temperature rise for bearings as well. At the others speed, the high preload could improve the vibration performance of high speed spindle and the bearing temperature was lower than that of the constant pressure preload spindle.

Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles.

Science.gov (United States)

Decker, Franziska; Oriola, David; Dalton, Benjamin; Brugués, Jan

2018-01-11

Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting. © 2018, Decker et al.

A SUMOylation Motif in Aurora-A: Implications for Spindle Dynamics and Oncogenesis

Energy Technology Data Exchange (ETDEWEB)

Pérez de Castro, Ignacio; Aguirre-Portolés, Cristina [Molecular Oncology Programme, Cell Division and Cancer Group, Centro Nacional de Investigaciones Oncológicas, Madrid (Spain); Martin, Benedicte [CNRS-UMR 6061, Institut de Génétique et Développement de Rennes, IFR 140 GFAS, Faculté de Médecine, Université Rennes 1, Rennes (France); Fernández-Miranda, Gonzalo [Molecular Oncology Programme, Cell Division and Cancer Group, Centro Nacional de Investigaciones Oncológicas, Madrid (Spain); Klotzbucher, Andrea; Kubbutat, Michael H. G. [ProQinase GmBH, Freiburg (Germany); Megías, Diego [Confocal Microscopy Core Unit, Centro Nacional de Investigaciones Oncológicas, Madrid (Spain); Arlot-Bonnemains, Yannick [CNRS-UMR 6061, Institut de Génétique et Développement de Rennes, IFR 140 GFAS, Faculté de Médecine, Université Rennes 1, Rennes (France); Malumbres, Marcos, E-mail: mmm@cnio.es, E-mail: iperez@cnio.es [Molecular Oncology Programme, Cell Division and Cancer Group, Centro Nacional de Investigaciones Oncológicas, Madrid (Spain)

2011-12-14

Aurora-A is a serine/threonine kinase that plays critical roles in centrosome maturation, spindle dynamics, and chromosome orientation and it is frequently over-expressed in human cancers. In this work, we show that Aurora-A interacts with the SUMO-conjugating enzyme UBC9 and co-localizes with SUMO1 in mitotic cells. Aurora-A can be SUMOylated in vitro and in vivo. Mutation of the highly conserved SUMOylation residue lysine 249 significantly disrupts Aurora-A SUMOylation and mitotic defects characterized by defective and multipolar spindles ensue. The Aurora-A{sup K249R} mutant has normal kinase activity but displays altered dynamics at the mitotic spindle. In addition, ectopic expression of the Aurora-A{sup K249R} mutant results in a significant increase in susceptibility to malignant transformation induced by the Ras oncogene. These data suggest that modification by SUMO residues may control Aurora-A function at the spindle and that deficiency of SUMOylation of this kinase may have important implications for tumor development.

Cortical dendritic activity correlates with spindle-rich oscillations during sleep in rodents.

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Seibt, Julie; Richard, Clément J; Sigl-Glöckner, Johanna; Takahashi, Naoya; Kaplan, David I; Doron, Guy; de Limoges, Denis; Bocklisch, Christina; Larkum, Matthew E

2017-09-25

How sleep influences brain plasticity is not known. In particular, why certain electroencephalographic (EEG) rhythms are linked to memory consolidation is poorly understood. Calcium activity in dendrites is known to be necessary for structural plasticity changes, but this has never been carefully examined during sleep. Here, we report that calcium activity in populations of neocortical dendrites is increased and synchronised during oscillations in the spindle range in naturally sleeping rodents. Remarkably, the same relationship is not found in cell bodies of the same neurons and throughout the cortical column. Spindles during sleep have been suggested to be important for brain development and plasticity. Our results provide evidence for a physiological link of spindles in the cortex specific to dendrites, the main site of synaptic plasticity.Different stages of sleep, marked by particular electroencephalographic (EEG) signatures, have been linked to memory consolidation, but underlying mechanisms are poorly understood. Here, the authors show that dendritic calcium synchronisation correlates with spindle-rich sleep phases.

Clathrin is spindle-associated but not essential for mitosis.

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Joana Borlido

Full Text Available Clathrin is a multimeric protein involved in vesicle coat assembly. Recently clathrin distribution was reported to change during the cell cycle and was found to associate with the mitotic spindle. Here we test whether the recruitment of clathrin to the spindle is indicative of a critical functional contribution to mitosis.Previously a chicken pre-B lymphoma cell line (DKO-R was developed in which the endogenous clathrin heavy chain alleles were replaced with the human clathrin heavy chain under the control of a tetracycline-regulatable promoter. Receptor-mediated and fluid-phase endocytosis were significantly inhibited in this line following clathrin knockout, and we used this to explore the significance of clathrin heavy chain expression for cell cycle progression. We confirmed using confocal microscopy that clathrin colocalised with tubulin at mitotic spindles. Using a propidium iodide flow cytometric assay we found no statistical difference in the cell cycle distribution of the knockout cells versus the wild-type. Additionally, we showed that the ploidy and the recovery kinetics following cell cycle arrest with nocodazole were unchanged by repressing clathrin heavy chain expression.We conclude that the association of clathrin with the mitotic spindle and the contribution of clathrin to endocytosis are evolutionarily conserved. However we find that the contribution of clathrin to mitosis is less robust and dependent on cellular context. In other cell-lines silencing RNA has been used by others to knockdown clathrin expression resulting in an increase in the mitotic index of the cells. We show an effect on the G2/M phase population of clathrin knockdown in HEK293 cells but show that repressing clathrin expression in the DKO-R cell-line has no effect on the size of this population. Consequently this work highlights the need for a more detailed molecular understanding of the recruitment and function of clathrin at the spindle, since the

Elongational flow of polymer melts at constant strain rate, constant stress and constant force

Science.gov (United States)

Wagner, Manfred H.; Rolón-Garrido, Víctor H.

2013-04-01

Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.

Sleep Spindles in the Right Hemisphere Support Awareness of Regularities and Reflect Pre-Sleep Activations.

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Yordanova, Juliana; Kolev, Vasil; Bruns, Eike; Kirov, Roumen; Verleger, Rolf

2017-11-01

The present study explored the sleep mechanisms which may support awareness of hidden regularities. Before sleep, 53 participants learned implicitly a lateralized variant of the serial response-time task in order to localize sensorimotor encoding either in the left or right hemisphere and induce implicit regularity representations. Electroencephalographic (EEG) activity was recorded at multiple electrodes during both task performance and sleep, searching for lateralized traces of the preceding activity during learning. Sleep EEG analysis focused on region-specific slow (9-12 Hz) and fast (13-16 Hz) sleep spindles during nonrapid eye movement sleep. Fast spindle activity at those motor regions that were activated during learning increased with the amount of postsleep awareness. Independently of side of learning, spindle activity at right frontal and fronto-central regions was involved: there, fast spindles increased with the transformation of sequence knowledge from implicit before sleep to explicit after sleep, and slow spindles correlated with individual abilities of gaining awareness. These local modulations of sleep spindles corresponded to regions with greater presleep activation in participants with postsleep explicit knowledge. Sleep spindle mechanisms are related to explicit awareness (1) by tracing the activation of motor cortical and right-hemisphere regions which had stronger involvement already during learning and (2) by recruitment of individually consolidated processing modules in the right hemisphere. The integration of different sleep spindle mechanisms with functional states during wake collectively supports the gain of awareness of previously experienced regularities, with a special role for the right hemisphere. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Warts phosphorylates mud to promote pins-mediated mitotic spindle orientation in Drosophila, independent of Yorkie.

Science.gov (United States)

Dewey, Evan B; Sanchez, Desiree; Johnston, Christopher A

2015-11-02

Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here, we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily conserved cell proliferation pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fusimotor control of spindle sensitivity regulates central and peripheral coding of joint angles.

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Lan, Ning; He, Xin

2012-01-01

Proprioceptive afferents from muscle spindles encode information about peripheral joint movements for the central nervous system (CNS). The sensitivity of muscle spindle is nonlinearly dependent on the activation of gamma (γ) motoneurons in the spinal cord that receives inputs from the motor cortex. How fusimotor control of spindle sensitivity affects proprioceptive coding of joint position is not clear. Furthermore, what information is carried in the fusimotor signal from the motor cortex to the muscle spindle is largely unknown. In this study, we addressed the issue of communication between the central and peripheral sensorimotor systems using a computational approach based on the virtual arm (VA) model. In simulation experiments within the operational range of joint movements, the gamma static commands (γ(s)) to the spindles of both mono-articular and bi-articular muscles were hypothesized (1) to remain constant, (2) to be modulated with joint angles linearly, and (3) to be modulated with joint angles nonlinearly. Simulation results revealed a nonlinear landscape of Ia afferent with respect to both γ(s) activation and joint angle. Among the three hypotheses, the constant and linear strategies did not yield Ia responses that matched the experimental data, and therefore, were rejected as plausible strategies of spindle sensitivity control. However, if γ(s) commands were quadratically modulated with joint angles, a robust linear relation between Ia afferents and joint angles could be obtained in both mono-articular and bi-articular muscles. With the quadratic strategy of spindle sensitivity control, γ(s) commands may serve as the CNS outputs that inform the periphery of central coding of joint angles. The results suggest that the information of joint angles may be communicated between the CNS and muscles via the descending γ(s) efferent and Ia afferent signals.

Modulation of jaw muscle spindle afferent activity following intramuscular injections with hypertonic saline.

Science.gov (United States)

Ro, J Y; Capra, N F

2001-05-01

Transient noxious chemical stimulation of small diameter muscle afferents modulates jaw movement-related responses of caudal brainstem neurons. While it is likely that the effect is mediated from the spindle afferents in the mesencephalic nucleus (Vmes) via the caudally projecting Probst's tract, the mechanisms of pain induced modulations of jaw muscle spindle afferents is not known. In the present study, we tested the hypothesis that jaw muscle nociceptors gain access to muscle spindle afferents in the same muscle via central mechanisms and alter their sensitivity. Thirty-five neurons recorded from the Vmes were characterized as muscle spindle afferents based on their responses to passive jaw movements, muscle palpation, and electrical stimulation of the masseter nerve. Each cell was tested by injecting a small volume (250 microl) of either 5% hypertonic and/or isotonic saline into the receptor-bearing muscle. Twenty-nine units were tested with 5% hypertonic saline, of which 79% (23/29) showed significant modulation of mean firing rates (MFRs) during one or more phases of ramp-and-hold movements. Among the muscle spindle primary-like units (n = 12), MFRs of 4 units were facilitated, five reduced, two showed mixed responses and one unchanged. In secondary-like units (n = 17), MFRs of 9 were facilitated, three reduced and five unchanged. Thirteen units were tested with isotonic saline, of which 77% showed no significant changes of MFRs. Further analysis revealed that the hypertonic saline not only affected the overall output of muscle spindle afferents, but also increased the variability of firing and altered the relationship between afferent signal and muscle length. These results demonstrated that activation of muscle nociceptors significantly affects proprioceptive properties of jaw muscle spindles via central neural mechanisms. The changes can have deleterious effects on oral motor function as well as kinesthetic sensibility.

Validation of a novel automatic sleep spindle detector with high performance during sleep in middle aged subjects

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Christensen, Julie A. E.; Kempfner, Jacob

2012-01-01

Many of the automatic sleep spindle detectors currently used to analyze sleep EEG are either validated on young subjects or not validated thoroughly. The purpose of this study is to develop and validate a fast and reliable sleep spindle detector with high performance in middle aged subjects....... An automatic sleep spindle detector using a bandpass filtering approach and a time varying threshold was developed. The validation was done on sleep epochs from EEG recordings with manually scored sleep spindles from 13 healthy subjects with a mean age of 57.9 ± 9.7 years. The sleep spindle detector reached...

Spindle frequency activity in the sleep EEG: individual differences and topographic distribution.

Science.gov (United States)

Werth, E; Achermann, P; Dijk, D J; Borbély, A A

1997-11-01

The brain topography of EEG power spectra in the frequency range of sleep spindles was investigated in 34 sleep recordings from 20 healthy young men. Referential (F3-A2, C3-A2, P3-A2 and O1-A2) and bipolar derivations (F3-C3, C3-P3 and P3-O1) along the anteroposterior axis were used. Sleep spindles gave rise to a distinct peak in the EEG power spectrum. The distribution of the peak frequencies pooled over subjects and derivations showed a bimodal pattern with modes at 11.5 and 13.0 Hz, and a trough at 12.25 Hz. The large inter-subject variation in peak frequency (range: 1.25 Hz) contrasted with the small intra-subject variation between derivations, non-REM sleep episodes and different nights. In some individuals and/or some derivations, only a single spindle peak was present. The topographic distributions from referential and bipolar recordings showed differences. The power showed a declining trend over consecutive non-REM sleep episodes in the low range of spindle frequency activity and a rising trend in the high range. The functional and topographic heterogeneity of sleep spindles in conjunction with the intra-subject stability of their frequency are important characteristics for the analysis of sleep regulation on the basis of the EEG.

Left atrial spindle cell sarcoma – Case report

Directory of Open Access Journals (Sweden)

Nihar Mehta

2012-07-01

Full Text Available Primary spindle cell sarcoma of the left atrium is an extremely rare tumour. Surgical excision is the mainstay of treatment since it responds poorly to chemotherapy or radiotherapy. In spite of all the treatment, the prognosis remains poor due to inadvertent delay in diagnosis, few therapeutic options and propensity to metastasize. We present a 47-year-old male who underwent a surgical excision of a left atrial mass in February 2010. It was proved to be a high-grade spindle cell sarcoma on histopathology. He presented again in October 2010 with recurrence of the tumour for which he was re-operated. However, the tumour recurred again within one month, to which the patient succumbed.

Sleep-spindle detection: crowdsourcing and evaluating performance of experts, non-experts and automated methods

DEFF Research Database (Denmark)

Warby, Simon C.; Wendt, Sabrina Lyngbye; Welinder, Peter

2014-01-01

to crowdsource spindle identification by human experts and non-experts, and we compared their performance with that of automated detection algorithms in data from middle- to older-aged subjects from the general population. We also refined methods for forming group consensus and evaluating the performance...... of event detectors in physiological data such as electroencephalographic recordings from polysomnography. Compared to the expert group consensus gold standard, the highest performance was by individual experts and the non-expert group consensus, followed by automated spindle detectors. This analysis showed...... that crowdsourcing the scoring of sleep data is an efficient method to collect large data sets, even for difficult tasks such as spindle identification. Further refinements to spindle detection algorithms are needed for middle- to older-aged subjects....

Synthesis and surface modification of spindle-type magnetic nanoparticles: gold coating and PEG functionalization

OpenAIRE

Mendez-Garza , Juan; Wang , Biran; Madeira , Alexandra; Di-Giorgio , Christophe; Bossis , Georges

2013-01-01

International audience; In this paper, we describe the synthesis of gold coated spindle-type iron nanoparticles and its surface modification by a thiolated fluorescently-labelled polyethylene glycol (PEG) polymer. A forced hydrolysis of ferric salts in the presence of phosphate ions was used to produce α-Fe2O3 spindle-type particles. The oxide powders were first reduced to α-iron under high temperature and controlled dihydrogen atmosphere. Then, the resulting magnetic spindle-type particles w...

White Matter Structure in Older Adults Moderates the Benefit of Sleep Spindles on Motor Memory Consolidation.

Science.gov (United States)

Mander, Bryce A; Zhu, Alyssa H; Lindquist, John R; Villeneuve, Sylvia; Rao, Vikram; Lu, Brandon; Saletin, Jared M; Ancoli-Israel, Sonia; Jagust, William J; Walker, Matthew P

2017-11-29

Sleep spindles promote the consolidation of motor skill memory in young adults. Older adults, however, exhibit impoverished sleep-dependent motor memory consolidation. The underlying pathophysiological mechanism(s) explaining why motor memory consolidation in older adults fails to benefit from sleep remains unclear. Here, we demonstrate that male and female older adults show impoverished overnight motor skill memory consolidation relative to young adults, with the extent of impairment being associated with the degree of reduced frontal fast sleep spindle density. The magnitude of the loss of frontal fast sleep spindles in older adults was predicted by the degree of reduced white matter integrity throughout multiple white matter tracts known to connect subcortical and cortical brain regions. We further demonstrate that the structural integrity of selective white matter fiber tracts, specifically within right posterior corona radiata, right tapetum, and bilateral corpus callosum, statistically moderates whether sleep spindles promoted overnight consolidation of motor skill memory. Therefore, white matter integrity within tracts known to connect cortical sensorimotor control regions dictates the functional influence of sleep spindles on motor skill memory consolidation in the elderly. The deterioration of white matter fiber tracts associated with human brain aging thus appears to be one pathophysiological mechanism influencing subcortical-cortical propagation of sleep spindles and their related memory benefits. SIGNIFICANCE STATEMENT Numerous studies have shown that sleep spindle expression is reduced and sleep-dependent motor memory is impaired in older adults. However, the mechanisms underlying these alterations have remained unknown. The present study reveals that age-related degeneration of white matter within select fiber tracts is associated with reduced sleep spindles in older adults. We further demonstrate that, within these same fiber tracts, the degree of

The pacemaker role of thalamic reticular nucleus in controlling spike-wave discharges and spindles.

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Fan, Denggui; Liao, Fucheng; Wang, Qingyun

2017-07-01

Absence epilepsy, characterized by 2-4 Hz spike-wave discharges (SWDs), can be caused by pathological interactions within the thalamocortical system. Cortical spindling oscillations are also demonstrated to involve the oscillatory thalamocortical rhythms generated by the synaptic circuitry of the thalamus and cortex. This implies that SWDs and spindling oscillations can share the common thalamocortical mechanism. Additionally, the thalamic reticular nucleus (RE) is hypothesized to regulate the onsets and propagations of both the epileptic SWDs and sleep spindles. Based on the proposed single-compartment thalamocortical neural field model, we firstly investigate the stimulation effect of RE on the initiations, terminations, and transitions of SWDs. It is shown that the activations and deactivations of RE triggered by single-pulse stimuli can drive the cortical subsystem to behave as the experimentally observed onsets and self-abatements of SWDs, as well as the transitions from 2-spike and wave discharges (2-SWDs) to SWDs. In particular, with increasing inhibition from RE to the specific relay nucleus (TC), rich transition behaviors in cortex can be obtained through the upstream projection path, RE→TC→Cortex. Although some of the complex dynamical patterns can be expected from the earlier single compartment thalamocortical model, the effect of brain network topology on the emergence of SWDs and spindles, as well as the transitions between them, has not been fully investigated. We thereby develop a spatially extended 3-compartment coupled network model with open-/closed-end connective configurations, to investigate the spatiotemporal effect of RE on the SWDs and spindles. Results show that the degrees of activations of RE 1 can induce the rich spatiotemporal evolution properties including the propagations from SWDs to spindles within different compartments and the transitions between them, through the RE 1 →TC 1 →Cortex 1 and Cortex 1 →Cortex 2 →Cortex 3

The pacemaker role of thalamic reticular nucleus in controlling spike-wave discharges and spindles

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Fan, Denggui; Liao, Fucheng; Wang, Qingyun

2017-07-01

Absence epilepsy, characterized by 2-4 Hz spike-wave discharges (SWDs), can be caused by pathological interactions within the thalamocortical system. Cortical spindling oscillations are also demonstrated to involve the oscillatory thalamocortical rhythms generated by the synaptic circuitry of the thalamus and cortex. This implies that SWDs and spindling oscillations can share the common thalamocortical mechanism. Additionally, the thalamic reticular nucleus (RE) is hypothesized to regulate the onsets and propagations of both the epileptic SWDs and sleep spindles. Based on the proposed single-compartment thalamocortical neural field model, we firstly investigate the stimulation effect of RE on the initiations, terminations, and transitions of SWDs. It is shown that the activations and deactivations of RE triggered by single-pulse stimuli can drive the cortical subsystem to behave as the experimentally observed onsets and self-abatements of SWDs, as well as the transitions from 2-spike and wave discharges (2-SWDs) to SWDs. In particular, with increasing inhibition from RE to the specific relay nucleus (TC), rich transition behaviors in cortex can be obtained through the upstream projection path, RE → TC → Cortex . Although some of the complex dynamical patterns can be expected from the earlier single compartment thalamocortical model, the effect of brain network topology on the emergence of SWDs and spindles, as well as the transitions between them, has not been fully investigated. We thereby develop a spatially extended 3-compartment coupled network model with open-/closed-end connective configurations, to investigate the spatiotemporal effect of RE on the SWDs and spindles. Results show that the degrees of activations of RE 1 can induce the rich spatiotemporal evolution properties including the propagations from SWDs to spindles within different compartments and the transitions between them, through the RE 1 → TC 1 → Cortex 1 and Cortex 1 → Cortex 2 �

Online Dynamic Balance Technology for High Speed Spindle Based on Gain Parameter Adaption and Scheduling Control

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Shihai Zhang

2018-06-01

Full Text Available Unbalance vibration is one of the main vibration forms of a high speed machine tool spindle. The overlarge unbalance vibration will have some adverse effects on the working life of the spindle system and the surface quality of the work-piece. In order to reduce the unbalance of a high speed spindle system, a pneumatic online dynamic balance device and its control system are presented in the paper. To improve the balance accuracy and adaptation of the balance system, the gain parameter adaption and scheduling control method are proposed first, and then the different balance effects of the influence coefficient method and the gain scheduling control method are compared through many dynamic balance experiments of the high speed spindle. The experimental results indicate that the gain parameters can be changed timely according to the transformation of the speed and kinetic parameters of the spindle system. The balance accuracy can be improved for a high speed spindle with time-varying characteristics, based on the adaptive gain scheduling control method.

The effects of eszopiclone on sleep spindles and memory consolidation in schizophrenia: a randomized placebo-controlled trial.

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Wamsley, Erin J; Shinn, Ann K; Tucker, Matthew A; Ono, Kim E; McKinley, Sophia K; Ely, Alice V; Goff, Donald C; Stickgold, Robert; Manoach, Dara S

2013-09-01

In schizophrenia there is a dramatic reduction of sleep spindles that predicts deficient sleep-dependent memory consolidation. Eszopiclone (Lunesta), a non-benzodiazepine hypnotic, acts on γ-aminobutyric acid (GABA) neurons in the thalamic reticular nucleus where spindles are generated. We investigated whether eszopiclone could increase spindles and thereby improve memory consolidation in schizophrenia. In a double-blind design, patients were randomly assigned to receive either placebo or 3 mg of eszopiclone. Patients completed Baseline and Treatment visits, each consisting of two consecutive nights of polysomnography. On the second night of each visit, patients were trained on the motor sequence task (MST) at bedtime and tested the following morning. Academic research center. Twenty-one chronic, medicated schizophrenia outpatients. We compared the effects of two nights of eszopiclone vs. placebo on stage 2 sleep spindles and overnight changes in MST performance. Eszopiclone increased the number and density of spindles over baseline levels significantly more than placebo, but did not significantly enhance overnight MST improvement. In the combined eszopiclone and placebo groups, spindle number and density predicted overnight MST improvement. Eszopiclone significantly increased sleep spindles, which correlated with overnight motor sequence task improvement. These findings provide partial support for the hypothesis that the spindle deficit in schizophrenia impairs sleep-dependent memory consolidation and may be ameliorated by eszopiclone. Larger samples may be needed to detect a significant effect on memory. Given the general role of sleep spindles in cognition, they offer a promising novel potential target for treating cognitive deficits in schizophrenia.

CD30+ lymphoproliferative disorder with spindle-cell morphology.

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Martires, Kathryn J; Cohen, Brandon E; Cassarino, David S

2016-11-01

Lymphomatoid papulosis (LyP) is classified as a CD30+ primary cutaneous lymphoproliferative disease. The phenotypic variability along the spectrum of CD30+ lymphoproliferative diseases is highlighted by the distinct histologic subtypes of LyP types A, B, C, and the more recently described types D, E, and F. We report the case of an elderly woman with a clinical presentation and histopathologic findings consistent with LyP, whose atypical CD30+ infiltrate uniquely demonstrated a spindle-cell morphology. To our knowledge, this is the first reported case of LyP characterized by CD30+ spindle-shaped cells, and may represent a new and distinct histologic variant of LyP. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Clathrin heavy chain 1 is required for spindle assembly and chromosome congression in mouse oocytes.

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Zhao, Jie; Wang, Lu; Zhou, Hong-Xia; Liu, Li; Lu, Angeleem; Li, Guang-Peng; Schatten, Heide; Liang, Cheng-Guang

2013-10-01

Clathrin heavy chain 1 (CLTC) has been considered a “moonlighting protein” which acts in membrane trafficking during interphase and in stabilizing spindle fibers during mitosis. However, its roles in meiosis, especially in mammalian oocyte maturation, remain unclear. This study investigated CLTC expression and function in spindle formation and chromosome congression during mouse oocyte meiotic maturation. Our results showed that the expression level of CLTC increased after germinal vesicle breakdown (GVBD) and peaked in the M phase. Immunostaining results showed CLTC distribution throughout the cytoplasm in a cell cycle-dependent manner. Appearance and disappearance of CLTC along with β-tubulin (TUBB) could be observed during spindle dynamic changes. To explore the relationship between CLTC and microtubule dynamics, oocytes at metaphase were treated with taxol or nocodazole. CLTC colocalized with TUBB at the enlarged spindle and with cytoplasmic asters after taxol treatment; it disassembled and distributed into the cytoplasm along with TUBB after nocodazole treatment. Disruption of CLTC function using stealth siRNA caused a decreased first polar body extrusion rate and extensive spindle formation and chromosome congression defects. Taken together, these results show that CLTC plays an important role in spindle assembly and chromosome congression through a microtubule correlation mechanism during mouse oocyte maturation.

Spindle Cell Metaplastic Breast Cancer: Case Report

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Dursun Ozgur Karakas

2013-08-01

Conclusion: Spindle cell metaplastic breast cancer must be considered in differential diagnosis of breast cancers, and preoperative immunohistochemical examination, including cytokeratin and vimentin, must be added to pathological examination in intervening cases. [Arch Clin Exp Surg 2013; 2(4.000: 259-262

Direct kinetochore?spindle pole connections are not required for chromosome segregation

OpenAIRE

Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B.; He, Jie; Le Berre, Ma?l; Tikhonenko, Irina; Ault, Jeffrey G.; McEwen, Bruce F.; Chen, James K.; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M.; Khodjakov, Alexey

2014-01-01

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes? kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the...

Observational Study on the Occurrence of Muscle Spindles in Human Digastric and Mylohyoideus Muscles

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Daniele Saverino

2014-01-01

Full Text Available Although the occurrence of muscle spindles (MS is quite high in most skeletal muscles of humans, few MS, or even absence, have been reported in digastric and mylohyoideus muscles. Even if this condition is generally accepted and quoted in many papers and books, observational studies are scarce and based on histological sections of a low number of specimens. The aim of the present study is to confirm previous data, assessing MS number in a sample of digastric and mylohyoideus muscles. We investigated 11 digastric and 6 mylohyoideus muscles from 13 donors. Muscle samples were embedded in paraffin wax, cross-sectioned in a rostrocaudal direction, and stained using haematoxylin-eosin. A mean of 5.1 ± 1.1 (range 3–7 MS was found in digastric muscles and mean of 0.5 ± 0.8 (range 0–2 in mylohyoideus muscles. A significant difference (P<0.001 was found with the control sample, confirming the correctness of the histological procedure. Our results support general belief that the absolute number of spindles is sparse in digastric and mylohyoideus muscles. External forces, such as food resistance during chewing or gravity, do not counteract jaw-opening muscles. It is conceivable that this condition gives them a limited proprioceptive importance and a reduced need for having specific receptors as MS.

Smurf2 as a novel mitotic regulator: From the spindle assembly checkpoint to tumorigenesis

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Moore Finola E

2009-07-01

Full Text Available Abstract The execution of the mitotic program with high fidelity is dependent upon precise spatiotemporal regulation of posttranslational protein modifications. For example, the timely polyubiquitination of critical mitotic regulators by Anaphase Promoting Complex/Cyclosome (APC/C is essential for the metaphase to anaphase transition and mitotic exit. The spindle assembly checkpoint prevents unscheduled activity of APC/C-Cdc20 in early mitosis, allowing bipolar attachment of kinetochores to mitotic spindle and facilitating equal segregation of sister chromatids. The critical effector of the spindle checkpoint, Mitotic arrest deficient 2 (Mad2, is recruited to unattached kinetochores forming a complex with other regulatory proteins to efficiently and cooperatively inhibit APC/C-Cdc20. A weakened and/or dysfunctional spindle checkpoint has been linked to the development of genomic instability in both cell culture and animal models, and evidence suggests that aberrant regulation of the spindle checkpoint plays a critical role in human carcinogenesis. Recent studies have illuminated a network of both degradative and non-degradative ubiquitination events that regulate the metaphase to anaphase transition and mitotic exit. Within this context, our recent work showed that the HECT (Homologous to E6-AP C-terminus-family E3 ligase Smurf2 (Smad specific ubiquitin regulatory factor 2, known as a negative regulator of transforming growth factor-beta (TGF-β signaling, is required for a functional spindle checkpoint by promoting the functional localization and stability of Mad2. Here we discuss putative models explaining the role of Smurf2 as a new regulator in the spindle checkpoint. The dynamic mitotic localization of Smurf2 to the centrosome and other critical mitotic structures provides implications about mitotic checkpoint control dependent on various ubiquitination events. Finally, deregulated Smurf2 activity may contribute to carcinogenesis by

Anaphase B

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Jonathan M. Scholey

2016-12-01

Full Text Available Anaphase B spindle elongation is characterized by the sliding apart of overlapping antiparallel interpolar (ip microtubules (MTs as the two opposite spindle poles separate, pulling along disjoined sister chromatids, thereby contributing to chromosome segregation and the propagation of all cellular life. The major biochemical “modules” that cooperate to mediate pole–pole separation include: (i midzone pushing or (ii braking by MT crosslinkers, such as kinesin-5 motors, which facilitate or restrict the outward sliding of antiparallel interpolar MTs (ipMTs; (iii cortical pulling by disassembling astral MTs (aMTs and/or dynein motors that pull aMTs outwards; (iv ipMT plus end dynamics, notably net polymerization; and (v ipMT minus end depolymerization manifest as poleward flux. The differential combination of these modules in different cell types produces diversity in the anaphase B mechanism. Combinations of antagonist modules can create a force balance that maintains the dynamic pre-anaphase B spindle at constant length. Tipping such a force balance at anaphase B onset can initiate and control the rate of spindle elongation. The activities of the basic motor filament components of the anaphase B machinery are controlled by a network of non-motor MT-associated proteins (MAPs, for example the key MT cross-linker, Ase1p/PRC1, and various cell-cycle kinases, phosphatases, and proteases. This review focuses on the molecular mechanisms of anaphase B spindle elongation in eukaryotic cells and briefly mentions bacterial DNA segregation systems that operate by spindle elongation.

Thermal Error Modelling of the Spindle Using Data Transformation and Adaptive Neurofuzzy Inference System

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Yanlei Li

2015-01-01

Full Text Available This paper proposes a new method for predicting spindle deformation based on temperature data. The method introduces the adaptive neurofuzzy inference system (ANFIS, which is a neurofuzzy modeling approach that integrates the kernel and geometrical transformations. By utilizing data transformation, the number of ANFIS rules can be effectively reduced and the predictive model structure can be simplified. To build the predictive model, we first map the original temperature data to a feature space with Gaussian kernels. We then process the mapped data with the geometrical transformation and make the data gather in the square region. Finally, the transformed data are used as input to train the ANFIS. A verification experiment is conducted to evaluate the performance of the proposed method. Six Pt100 thermal resistances are used to monitor the spindle temperature, and a laser displacement sensor is used to detect the spindle deformation. Experimental results show that the proposed method can precisely predict the spindle deformation and greatly improve the thermal performance of the spindle. Compared with back propagation (BP networks, the proposed method is more suitable for complex working conditions in practical applications.

Synthesis of Elongated Microcapsules

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Li, Wenyan; Buhrow, Jerry; Calle, Luz M.

2011-01-01

One of the factors that influence the effectiveness of self-healing in functional materials is the amount of liquid healing agents that can be delivered to the damaged area. The use of hollow tubes or fibers and the more sophisticated micro-vascular networks has been proposed as a way to increase the amount of healing agents that can be released when damage is inflicted. Although these systems might be effective in some specific applications, they are not practical for coatings applications. One possible practical way to increase the healing efficiency is to use microcapsules with high-aspect-ratios, or elongated microcapsules. It is understood that elongated microcapsules will be more efficient because they can release more healing agent than a spherical microcapsule when a crack is initiated in the coating. Although the potential advantage of using elongated microcapsules for self healing applications is clear, it is very difficult to make elongated microcapsules from an emulsion system because spherical microcapsules are normally formed due to the interfacial tension between the dispersed phase and the continuous phase. This paper describes the two methods that have been developed by the authors to synthesize elongated microcapsules. The first method involves the use of an emulsion with intermediate stability and the second involves the application of mechanical shear conditions to the emulsion.

Cytokeratin: a Shortcut to Diagnose Spindle Cell Carcinoma

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Dehghani Nazhvani A

2017-09-01

Full Text Available A relatively rare subtype of squamous cell carcinoma (SCC is spindle cell carcinoma (SPCC. It is composed of epithelium-derived spindle cells arranged in sheets with mesenchymal properties and small, hard-ly detectable regions of SCC, challenging its definite diagnosis. We encountered five cases of SPCC. In case one, chronic inflammation and subepithelial blister with leukoplakia was found 5 years before our examination. And later, exophytic features, keratotic papules and scar with elevated margins was seen on lateral border of the tongue. In case two, three and four, an abnormal soft tissue elevations were examined, and in the fifth case we examined the soft and bony speci-men from the posterior aspect of maxillary ridge. We evaluated all of them histologically and immunohistochemically for cytokeratin to reach final diagnosis.

Declarative memory performance is associated with the number of sleep spindles in elderly women.

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Seeck-Hirschner, Mareen; Baier, Paul Christian; Weinhold, Sara Lena; Dittmar, Manuela; Heiermann, Steffanie; Aldenhoff, Josef B; Göder, Robert

2012-09-01

Recent evidence suggests that the sleep-dependent consolidation of declarative memory relies on the nonrapid eye movement rather than the rapid eye movement phase of sleep. In addition, it is known that aging is accompanied by changes in sleep and memory processes. Hence, the purpose of this study was to investigate the overnight consolidation of declarative memory in healthy elderly women. Sleep laboratory of University. Nineteen healthy elderly women (age range: 61-74 years). We used laboratory-based measures of sleep. To test declarative memory, the Rey-Osterrieth Complex Figure Test was performed. Declarative memory performance in elderly women was associated with Stage 2 sleep spindle density. Women characterized by high memory performance exhibited significantly higher numbers of sleep spindles and higher spindle density compared with women with generally low memory performance. The data strongly support theories suggesting a link between sleep spindle activity and declarative memory consolidation.

Constitutive Cdk2 activity promotes aneuploidy while altering the spindle assembly and tetraploidy checkpoints

DEFF Research Database (Denmark)

Jahn, Stephan C; Corsino, Patrick E; Davis, Bradley J

2013-01-01

instability. Expression of these complexes in the MCF10A cell line leads to retinoblastoma protein (Rb) hyperphosphorylation, a subsequent increase in proliferation rate, and increased expression of the spindle assembly checkpoint protein Mad2. This results in a strengthening of the spindle assembly...

Radiation-induced spindle cell sarcoma: A rare case report

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Khan Mubeen

2009-01-01

Full Text Available Ionizing radiation has been known to induce malignant transformation in human beings. Radiation-induced sarcomas are a late sequel of radiation therapy. Most sarcomas have been reported to occur after exposure to a radiation dose of 55 Gray (Gy and above, with a dose ranging from 16 to 112 Gys. Spindle cell sarcomas, arising after radiotherapy given to treat the carcinoma of head and neck region is a very uncommon sequel. This is a rare case report of spindle cell sarcoma of left maxilla, in a 24-year-old male, occurring as a late complication of radiotherapy with Cobalt-60 given for the treatment of retinoblastoma of the left eye 21 years back.

Method for automated building of spindle thermal model with use of CAE system

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Kamenev, S. V.

2018-03-01

The spindle is one of the most important units of the metal-cutting machine tool. Its performance is critical to minimize the machining error, especially the thermal error. Various methods are applied to improve the thermal behaviour of spindle units. One of the most important methods is mathematical modelling based on the finite element analysis. The most common approach for its realization is the use of CAE systems. This approach, however, is not capable to address the number of important effects that need to be taken into consideration for proper simulation. In the present article, the authors propose the solution to overcome these disadvantages using automated thermal model building for the spindle unit utilizing the CAE system ANSYS.

Design of Accelerated Reliability Test for CNC Motorized Spindle Based on Vibration Signal

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Chen Chao

2016-01-01

Full Text Available Motorized spindle is the key functional component of CNC machining centers which is a mechatronics system with long life and high reliability. The reliability test cycle of motorized spindle is too long and infeasible. This paper proposes a new accelerated test for reliability evaluation of motorized spindle. By field reliability test, authors collect and calculate the load data including rotational speed, cutting force and torque. Load spectrum distribution law is analyzed. And authors design a test platform to apply the load spectrum. A new method to define the fuzzy acceleration factor based on the vibration signal is proposed. Then the whole test plan of accelerated reliability test is done.

JMJD5 (Jumonji Domain-containing 5) Associates with Spindle Microtubules and Is Required for Proper Mitosis.

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He, Zhimin; Wu, Junyu; Su, Xiaonan; Zhang, Ye; Pan, Lixia; Wei, Huimin; Fang, Qiang; Li, Haitao; Wang, Da-Liang; Sun, Fang-Lin

2016-02-26

Precise mitotic spindle assembly is a guarantee of proper chromosome segregation during mitosis. Chromosome instability caused by disturbed mitosis is one of the major features of various types of cancer. JMJD5 has been reported to be involved in epigenetic regulation of gene expression in the nucleus, but little is known about its function in mitotic process. Here we report the unexpected localization and function of JMJD5 in mitotic progression. JMJD5 partially accumulates on mitotic spindles during mitosis, and depletion of JMJD5 results in significant mitotic arrest, spindle assembly defects, and sustained activation of the spindle assembly checkpoint (SAC). Inactivating SAC can efficiently reverse the mitotic arrest caused by JMJD5 depletion. Moreover, JMJD5 is found to interact with tubulin proteins and associate with microtubules during mitosis. JMJD5-depleted cells show a significant reduction of α-tubulin acetylation level on mitotic spindles and fail to generate enough interkinetochore tension to satisfy the SAC. Further, JMJD5 depletion also increases the susceptibility of HeLa cells to the antimicrotubule agent. Taken together, these results suggest that JMJD5 plays an important role in regulating mitotic progression, probably by modulating the stability of spindle microtubules. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Combining time-frequency and spatial information for the detection of sleep spindles

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Christian eO'Reilly

2015-02-01

Full Text Available EEG sleep spindles are short (0.5-2.0 s bursts of activity in the 11-16 Hz band occurring during non-rapid eye movement (NREM sleep. This sporadic activity is thought to play a role in memory consolidation, brain plasticity, and protection of sleep integrity. Many automatic detectors have been proposed to assist or replace experts for sleep spindle scoring. However, these algorithms usually detect too many events making it difficult to achieve a good tradeoff between sensitivity (Se and false detection rate (FDr. In this work, we propose a semi-automatic detector comprising a sensitivity phase based on well-established criteria followed by a specificity phase using spatial and spectral criteria.In the sensitivity phase, selected events are those which amplitude in the 10 – 16 Hz band and spectral ratio characteristics both reject a null hypothesis (p <0.1 stating that the considered event is not a spindle. This null hypothesis is constructed from events occurring during rapid eye movement (REM sleep epochs. In the specificity phase, a hierarchical clustering of the selected candidates is done based on events’ frequency and spatial position along the anterior-posterior axis. Only events from the classes grouping most (at least 80% spindles scored by an expert are kept. We obtain Se = 93.2% and FDr = 93.0% in the first phase and Se = 85.4% and FDr = 86.2% in the second phase. For these two phases, Matthew’s correlation coefficients are respectively 0.228 and 0.324. Results suggest that spindles are defined by specific spatio-spectral properties and that automatic detection methods can be improved by considering these features.

Sleep Spindle Density Predicts the Effect of Prior Knowledge on Memory Consolidation

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Lambon Ralph, Matthew A.; Kempkes, Marleen; Cousins, James N.; Lewis, Penelope A.

2016-01-01

Information that relates to a prior knowledge schema is remembered better and consolidates more rapidly than information that does not. Another factor that influences memory consolidation is sleep and growing evidence suggests that sleep-related processing is important for integration with existing knowledge. Here, we perform an examination of how sleep-related mechanisms interact with schema-dependent memory advantage. Participants first established a schema over 2 weeks. Next, they encoded new facts, which were either related to the schema or completely unrelated. After a 24 h retention interval, including a night of sleep, which we monitored with polysomnography, participants encoded a second set of facts. Finally, memory for all facts was tested in a functional magnetic resonance imaging scanner. Behaviorally, sleep spindle density predicted an increase of the schema benefit to memory across the retention interval. Higher spindle densities were associated with reduced decay of schema-related memories. Functionally, spindle density predicted increased disengagement of the hippocampus across 24 h for schema-related memories only. Together, these results suggest that sleep spindle activity is associated with the effect of prior knowledge on memory consolidation. SIGNIFICANCE STATEMENT Episodic memories are gradually assimilated into long-term memory and this process is strongly influenced by sleep. The consolidation of new information is also influenced by its relationship to existing knowledge structures, or schemas, but the role of sleep in such schema-related consolidation is unknown. We show that sleep spindle density predicts the extent to which schemas influence the consolidation of related facts. This is the first evidence that sleep is associated with the interaction between prior knowledge and long-term memory formation. PMID:27030764

Experimental Analysis and Full Prediction Model of a 5-DOF Motorized Spindle

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Weiyu Zhang

2017-01-01

Full Text Available The cost and power consumption of DC power amplifiers are much greater than that of AC power converters. Compared to a motorized spindle supported with DC magnetic bearings, a motorized spindle supported with AC magnetic bearings is inexpensive and more efficient. This paper studies a five-degrees-of-freedom (5-DOF motorized spindle supported with AC hybrid magnetic bearings (HMBs. Most models of suspension forces, except a “switching model”, are quite accurate, but only in a particular operating area and not in regional coverage. If a “switching model” is applied to a 5-DOF motorized spindle, the real-time performance of the control system can be significantly decreased due to the large amount of data processing for both displacement and current. In order to solve this defect, experiments based on the “switching model” are performed, and the resulting data are analyzed. Using the data analysis results, a “full prediction model” based on the operating state is proposed to improve real-time performance and precision. Finally, comparative, verification and stiffness tests are conducted to verify the improvement of the proposed model. Results of the tests indicate that the rotor has excellent characteristics, such as good real-time performance, superior anti-interference performance with load and the accuracy of the model in full zone. The satisfactory experimental results demonstrate the effectiveness of the “full prediction model” applied to the control system under different operating stages. Therefore, the results of the experimental analysis and the proposed full prediction model can provide a control system of a 5-DOF motorized spindle with the most suitable mathematical models of the suspension force.

The function of the sleep spindle: a physiological index of intelligence and a mechanism for sleep-dependent memory consolidation.

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Fogel, Stuart M; Smith, Carlyle T

2011-04-01

Until recently, the electrophysiological mechanisms involved in strengthening new memories into a more permanent form during sleep have been largely unknown. The sleep spindle is an event in the electroencephalogram (EEG) characterizing Stage 2 sleep. Sleep spindles may reflect, at the electrophysiological level, an ideal mechanism for inducing long-term synaptic changes in the neocortex. Recent evidence suggests the spindle is highly correlated with tests of intellectual ability (e.g.; IQ tests) and may serve as a physiological index of intelligence. Further, spindles increase in number and duration in sleep following new learning and are correlated with performance improvements. Spindle density and sigma (14-16Hz) spectral power have been found to be positively correlated with performance following a daytime nap, and animal studies suggest the spindle is involved in a hippocampal-neocortical dialogue necessary for memory consolidation. The findings reviewed here collectively provide a compelling body of evidence that the function of the sleep spindle is related to intellectual ability and memory consolidation. Copyright © 2010 Elsevier Ltd. All rights reserved.

TFG-MET fusion in an infantile spindle cell sarcoma with neural features.

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Flucke, Uta; van Noesel, Max M; Wijnen, Marc; Zhang, Lei; Chen, Chun-Liang; Sung, Yun-Shao; Antonescu, Cristina R

2017-09-01

An increasing number of congenital and infantile sarcomas displaying a primitive, monomorphic spindle cell phenotype have been characterized to harbor recurrent gene fusions, including infantile fibrosarcoma and congenital spindle cell rhabdomyosarcoma. Here, we report an unusual spindle cell sarcoma presenting as a large and infiltrative pelvic soft tissue mass in a 4-month-old girl, which revealed a novel TFG-MET gene fusion by whole transcriptome RNA sequencing. The tumor resembled the morphology of an infantile fibrosarcoma with both fascicular and patternless growth, however, it expressed strong S100 protein immunoreactivity, while lacking SOX10 staining and retaining H3K27me3 expression. Although this immunoprofile suggested partial neural/neuroectodermal differentiation, overall features were unusual and did not fit into any known tumor types (cellular schwannoma, MPNST), raising the possibility of a novel pathologic entity. The TFG-MET gene fusion expands the genetic spectrum implicated in the pathogenesis of congenital spindle cell sarcomas, with yet another example of kinase oncogenic activation through chromosomal translocation. The discovery of this new fusion is significant since the resulting MET activation can potentially be inhibited by targeted therapy, as MET inhibitors are presently available in clinical trials. © 2017 Wiley Periodicals, Inc.

Elongational viscosity of narrow molar mass distribution polystyrene

DEFF Research Database (Denmark)

Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz

2003-01-01

Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly...

Time-frequency dynamics during sleep spindles on the EEG in rodents with a genetic predisposition to absence epilepsy (WAG/Rij rats)

Science.gov (United States)

Hramov, Alexander E.; Sitnikova, Evgenija Y.; Pavlov, Alexey N.; Grubov, Vadim V.; Koronovskii, Alexey A.; Khramova, Marina V.

2015-03-01

Sleep spindles are known to appear spontaneously in the thalamocortical neuronal network of the brain during slow-wave sleep; pathological processes in the thalamocortical network may be the reason of the absence epilepsy. The aim of the present work is to study developed changes in the time-frequency structure of sleep spindles during the progressive development of the absence epilepsy in WAG/Rij rats. EEG recordings were made at age 7 and 9 months. Automatic recognition and subsequent analysis of sleep spindles on the EEG were performed using the continuous wavelet transform. The duration of epileptic discharges and the total duration of epileptic activity were found to increase with age, while the duration of sleep spindles, conversely, decreased. In terms of the mean frequency, sleep spindles could be divided into three classes: `slow' (mean frequency 9.3Hz), `medium' (11.4Hz), and `fast' (13.5Hz). Slow and medium (transitional) spindles in five-month-old animals showed increased frequency from the beginning to the end of the spindle. The more intense the epilepsy is, the shorter are the durations of spindles of all types. The mean frequencies of `medium' and `fast' spindles were higher in rats with more intense signs of epilepsy. Overall, high epileptic activity in WAG/Rij rats was linked with significant changes in spindles of the transitional type, with less marked changes in the two traditionally identified types of spindle, slow and fast.

Sleep spindles are related to schizotypal personality traits and thalamic glutamine/glutamate in healthy subjects.

Science.gov (United States)

Lustenberger, Caroline; O'Gorman, Ruth L; Pugin, Fiona; Tüshaus, Laura; Wehrle, Flavia; Achermann, Peter; Huber, Reto

2015-03-01

Schizophrenia is a severe mental disorder affecting approximately 1% of the worldwide population. Yet, schizophrenia-like experiences (schizotypy) are very common in the healthy population, indicating a continuum between normal mental functioning and the psychosis found in schizophrenic patients. A continuum between schizotypy and schizophrenia would be supported if they share the same neurobiological origin. Two such neurobiological markers of schizophrenia are: (1) a reduction of sleep spindles (12-15 Hz oscillations during nonrapid eye movement sleep), likely reflecting deficits in thalamo-cortical circuits and (2) increased glutamine and glutamate (Glx) levels in the thalamus. Thus, this study aimed to investigate whether sleep spindles and Glx levels are related to schizotypal personality traits in healthy subjects. Twenty young male subjects underwent 2 all-night sleep electroencephalography recordings (128 electrodes). Sleep spindles were detected automatically. After those 2 nights, thalamic Glx levels were measured by magnetic resonance spectroscopy. Subjects completed a magical ideation scale to assess schizotypy. Sleep spindle density was negatively correlated with magical ideation (r = -.64, P .1). The common relationship of sleep spindle density with schizotypy and thalamic Glx levels indicates a neurobiological overlap between nonclinical schizotypy and schizophrenia. Thus, sleep spindle density and magical ideation may reflect the anatomy and efficiency of the thalamo-cortical system that shows pronounced impairment in patients with schizophrenia. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The Effect of the Rotor Static Eccentricity on the Electro-Mechanical Coupled Characteristics of the Motorized Spindle

Directory of Open Access Journals (Sweden)

Wu Zaixin

2016-01-01

Full Text Available High-speed motorized spindle is a multi-variable, non-linear and strong coupling system. The rotor static eccentricity is inevitable because of machining or assembling error. The rotor static eccentricities have an important effect on the electromechanical coupled characteristics of the motorized spindle. In this paper, the electromechanical coupled mathematical model of the motorized spindle was set up. The mathematical model includes mechanical and electrical equation. The mechanical and electrical equation is built up by the variational principle. Furthermore, the inductance parameters without the rotor static eccentricity and the inductance parameters with rotor static eccentricity have been calculated by the winding function method and the high speed motorized spindle was simulated. The result show that the rotor static eccentricity can delay the starting process of the motorized spindle, and at steady state, the rotor circuit currents are still large because of the rotor static eccentricity.

Analysis of radial runout for symmetric and asymmetric HDD spindle motors with rotor eccentricity

International Nuclear Information System (INIS)

Kim, T.-J.; Kim, K.-T.; Hwang, S.-M.; Lee, S.-B.; Park, N.-G.

2001-01-01

Radial runout of disk drive spindle is one of the major limiting factors in achieving higher track densities in hard disk drives. Mechanical, magnetic and their coupled origins, such as unbalanced mass, reaction forces and magnetic forces, introduce radial runout of spindle motors. In this paper, radial magnetic forces are calculated with respect to the various rotor eccentricities using analytic method. Based on the results of the radial magnetic forces, the radial runout of the spindle motor is analyzed using finite element and transfer matrices. Results show that an asymmetric motor has a worse performance on unbalanced magnetic forces and radial runout when mechanical and magnetic coupling exists

Muscle spindle autogenetic inhibition in the extraocular muscles of lamb.

Science.gov (United States)

Pettorossi, V E; Filippi, G M

1981-09-01

The role of extraocular muscle (EOM) proprioceptors on eye motility has been investigated in lambs on "encéphale isolé", by evaluating the tension of EOMs at various lengths and velocities of stretch before and after proprioceptive blocks. The EOM tension, in the absence of proprioceptive input, was higher than in normal conditions. Such an effect occurred at lengthening values greater than 3 mm of stretch from resting muscle length, corresponding to 18 degrees of eye deviation and was dependent on the velocity of the stretch, being more effective at high velocity. The muscle receptors responsible for this effect was determined by comparing the sensitivity to vibratory stimulation of spindles and tendon organs to the amount of inhibition provoked by the same stimulation on an EOM electromyographic activity. The tension inhibition appeared to be correlated to muscle spindle activation. Thus, the presence of muscle spindles can determine a reduction of the tension within the stretched muscles. This result suggests that the EOM length and velocity signals operate moment to moment reduction on the stiffness of the muscle which antagonizes eye displacement, thus facilitating the ocular movements.

Regulation of spindle orientation and neural stem cell fate in the Drosophila optic lobe

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Brand Andrea H

2007-01-01

Full Text Available Abstract Background The choice of a stem cell to divide symmetrically or asymmetrically has profound consequences for development and disease. Unregulated symmetric division promotes tumor formation, whereas inappropriate asymmetric division affects organ morphogenesis. Despite its importance, little is known about how spindle positioning is regulated. In some tissues cell fate appears to dictate the type of cell division, whereas in other tissues it is thought that stochastic variation in spindle position dictates subsequent sibling cell fate. Results Here we investigate the relationship between neural progenitor identity and spindle positioning in the Drosophila optic lobe. We use molecular markers and live imaging to show that there are two populations of progenitors in the optic lobe: symmetrically dividing neuroepithelial cells and asymmetrically dividing neuroblasts. We use genetically marked single cell clones to show that neuroepithelial cells give rise to neuroblasts. To determine if a change in spindle orientation can trigger a neuroepithelial to neuroblast transition, we force neuroepithelial cells to divide along their apical/basal axis by misexpressing Inscuteable. We find that this does not induce neuroblasts, nor does it promote premature neuronal differentiation. Conclusion We show that symmetrically dividing neuroepithelial cells give rise to asymmetrically dividing neuroblasts in the optic lobe, and that regulation of spindle orientation and division symmetry is a consequence of cell type specification, rather than a mechanism for generating cell type diversity.

Elongational viscosity of multiarm (Pom-Pom) polystyrene

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Almdal, Kristoffer

2006-01-01

-Pom was estimated to have 2.5 arms on average, while the estimate is 3.3 for the asymmetric star. The molar mass of each arm is about 27 kg/mol. The melts were characterized in the linear viscoelastic regime and in non-linear elongational rheometry. The transient elongational viscosity for the Pom-Pom molecule...... it corresponds well with an estimate of the maximum stretchability of the backbone. Time-strain separability was not observed for the 'Asymmetric star' molecule at the elongation rates investigated. The transient elongational viscosity for the 'Pom-Pom' molecule went through a reproducible maximum...... in the viscosity at the highest elongational rate....

Sleep spindle activity in double cortex syndrome: a case report.

Science.gov (United States)

Sforza, Emilia; Marcoz, Jean-Pierre; Foletti, Giovanni

2010-09-01

Cortical dysgenesis is increasingly recognised as a cause of epilepsy. We report a case with double cortex heterotopia and secondarily generalized seizures with a generalised spike wave pattern. During the course of the disease, the child developed electrical status epilepticus in slow wave sleep. From the first examination, sleep pattern revealed increased frequency and amplitude of spindle activity, more evident in anterior areas. The role of the thalamocortical pathway in increased sleep spindle activity is discussed with emphasis on the possible role of altered thalamocortical pathways in abnormal cortical migration. A strong suspicion of cortical dysgenesis may therefore be based on specific EEG sleep patterns.

Dishevelled binds the Discs large 'Hook' domain to activate GukHolder-dependent spindle positioning in Drosophila.

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Joshua D Garcia

Full Text Available Communication between cortical cell polarity cues and the mitotic spindle ensures proper orientation of cell divisions within complex tissues. Defects in mitotic spindle positioning have been linked to various developmental disorders and have recently emerged as a potential contributor to tumorigenesis. Despite the importance of this process to human health, the molecular mechanisms that regulate spindle orientation are not fully understood. Moreover, it remains unclear how diverse cortical polarity complexes might cooperate to influence spindle positioning. We and others have demonstrated spindle orientation roles for Dishevelled (Dsh, a key regulator of planar cell polarity, and Discs large (Dlg, a conserved apico-basal cell polarity regulator, effects which were previously thought to operate within distinct molecular pathways. Here we identify a novel direct interaction between the Dsh-PDZ domain and the alternatively spliced "I3-insert" of the Dlg-Hook domain, thus establishing a potential convergent Dsh/Dlg pathway. Furthermore, we identify a Dlg sequence motif necessary for the Dsh interaction that shares homology to the site of Dsh binding in the Frizzled receptor. Expression of Dsh enhanced Dlg-mediated spindle positioning similar to deletion of the Hook domain. This Dsh-mediated activation was dependent on the Dlg-binding partner, GukHolder (GukH. These results suggest that Dsh binding may regulate core interdomain conformational dynamics previously described for Dlg. Together, our results identify Dlg as an effector of Dsh signaling and demonstrate a Dsh-mediated mechanism for the activation of Dlg/GukH-dependent spindle positioning. Cooperation between these two evolutionarily-conserved cell polarity pathways could have important implications to both the development and maintenance of tissue homeostasis in animals.

The role of p53 in the response to mitotic spindle damage

International Nuclear Information System (INIS)

Meek, D.W.

2000-01-01

The p53 tumour suppressor protein has defined roles in G1/S and G2/M cell cycle checkpoint in response to a range of cellular stresses including DNA damage, dominant oncogene expression, hypoxia, metabolic changes and viral infection. In addition to these responses, p53 can also be activated when damage occurs to the mitotic spindle. Initially, spindle damage activates a p53-independent checkpoint which functions at the metaphase-anaphase transition and prevents cells from progressing through mitosis until the completion of spindle formation. Cells eventually escape from this block (a process termed 'mitotic slippage'), and an aberrant mitosis ensues in which sister chromatids fail to segregate properly. After a delay period, p53 responds to this mitotic failure by instituting a G1-like growth arrest, with an intact nucleus containing 4N DNA, but without the cells undergoing division. Cells lacking wild-type p53 are still able to arrest transiently at mitosis, and also fail to undergo division, underscoring that the delay in mitosis is p53-independent. However, these cells are not prevented from re-entering the cell cycle and can reduplicate their DNA unchecked, leading to polyploidy. Additionally, p53-null cells which experience spindle failure often show the appearance of micronuclei arising from poorly segregated chromosomes which have de-condensed and been enclosed in a nuclear envelope. The ability of p53 to prevent their formation suggests an additional G2 involvement which prevents nuclear breakdown prior to mitosis. The molecular mechanism by which p53 is able to sense mitotic failure is still unknown, but may be linked to the ability of p53 to regulate duplication of the centrosome, the organelle which nucleates spindle formation. (authors)

The Making of SPINdle

Science.gov (United States)

Lam, Ho-Pun; Governatori, Guido

We present the design and implementation of SPINdle - an open source Java based defeasible logic reasoner capable to perform efficient and scalable reasoning on defeasible logic theories (including theories with over 1 million rules). The implementation covers both the standard and modal extensions to defeasible logics. It can be used as a standalone theory prover and can be embedded into any applications as a defeasible logic rule engine. It allows users or agents to issues queries, on a given knowledge base or a theory generated on the fly by other applications, and automatically produces the conclusions of its consequences. The theory can also be represented using XML.

Abnormal spindles in second meiosis in canola (Brassica napus and Brassica campestris

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Alice Maria de Souza

1999-01-01

Full Text Available Studies were carried out on the occurrence of abnormal spindles in the second meiotic division in some canola cultivars recently introduced in Brazil. Fusion of spindles was observed in metaphase II rejoining the two sets of chromosomes segregated in anaphase I and also sequential and tripolar spindles were discovered rejoining two sets of chromatids segregated in anaphase II. The frequency of cells with abnormal spindles ranged from 3.18 to 8.10%. The results suggested that this abnormality was caused by environmental stress that affected the plants during the blooming period.O presente estudo descreve a ocorrência de fusos anormais na segunda divisão meiótica em algumas cultivares da canola recentemente introduzidas no Brasil. Fusão de fusos foi observada em metáfase II reunindo os dois conjuntos cromossômicos segregados na anáfase I; fusos sequenciais e tripolares reunindo cromátides segregadas na anáfase II também foram observados. A frequência de células com fusos anormais variou de 3,18 a 8,10% entre as variedades. Os resultados sugerem que estas anormalidades foram causadas por condições climáticas adversas que afetaram as plantas no período de florescimento. As implicações genéticas destas anormalidades são descritas.

Spindle assembly checkpoint acquisition at the mid-blastula transition.

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Maomao Zhang

Full Text Available The spindle assembly checkpoint (SAC maintains the fidelity of chromosome segregation during mitosis. Nonpathogenic cells lacking the SAC are typically only found in cleavage stage metazoan embryos, which do not acquire functional checkpoints until the mid-blastula transition (MBT. It is unclear how proper SAC function is acquired at the MBT, though several models exist. First, SAC acquisition could rely on transcriptional activity, which increases dramatically at the MBT. Embryogenesis prior to the MBT relies primarily on maternally loaded transcripts, and if SAC signaling components are not maternally supplied, the SAC would depend on zygotic transcription at the MBT. Second, checkpoint acquisition could depend on the Chk1 kinase, which is activated at the MBT to elongate cell cycles and is required for the SAC in somatic cells. Third, SAC function could depend on a threshold nuclear to cytoplasmic (N:C ratio, which increases during pre-MBT cleavage cycles and dictates several MBT events like zygotic transcription and cell cycle remodeling. Finally, the SAC could by regulated by a timer mechanism that coincides with other MBT events but is independent of them. Using zebrafish embryos we show that SAC acquisition at the MBT is independent of zygotic transcription, indicating that the checkpoint program is maternally supplied. Additionally, by precociously lengthening cleavage cycles with exogenous Chk1 activity, we show that cell cycle lengthening and Chk1 activity are not sufficient for SAC acquisition. Furthermore, we find that SAC acquisition can be uncoupled from the N:C ratio. Together, our findings indicate that SAC acquisition is regulated by a maternally programmed developmental timer.

Discrimination between micronuclei induced by spindle poisons and ...

African Journals Online (AJOL)

Discrimination between micronuclei induced by spindle poisons and clastogens by using toad bone marrow polychromatic erythrocytes. ... Egyptian Journal of Biology ... The used chemicals induced high percentages of micronuclei with variable sizes, which clarify the sensitivity of bone marrow cells of Bufo regularis to ...

Aphidicolin-induced nuclear elongation in tobacco BY-2 cells.

Science.gov (United States)

Yasuhara, Hiroki; Kitamoto, Kazuki

2014-05-01

Plant nuclei are known to differentiate into various shapes within a single plant. However, little is known about the mechanisms of nuclear morphogenesis. We found that nuclei of tobacco BY-2 cells were highly elongated on long-term treatment with 5 mg l⁻¹ aphidicolin, an inhibitor of DNA polymerase α. In aphidicolin-treated cells, the nuclear length was correlated with the cell length. During culture in the presence of aphidicolin, the nuclei were elongated in parallel with cell elongation. Nuclear elongation was inhibited by the inhibition of cell elongation with 2,6-dichlorobenzonitrile, a cellulose synthesis inhibitor. However, cell elongation induced in the auxin-depleted medium in the absence of aphidicolin did not cause nuclear elongation, indicating that cell elongation alone is not sufficient for nuclear elongation. Treatment with either latrunculin B or propyzamide inhibited the aphidicolin-induced nuclear elongation, indicating that both actin filaments and microtubules (MTs) are required for nuclear elongation. Observations using BY-YTHCLR2 cells, in which actin filaments, MTs and nuclei were simultaneously visualized, revealed that the longitudinally arranged MT bundles associated with the nucleus play an important role in nuclear elongation, and that actin filaments affect the formation of these MT bundles. In aphidicolin-treated cells, the nuclear DNA contents of the elongated nuclei exceeded 4C, and the nuclear length was highly correlated with the nuclear DNA content. In cells treated with 50 mg l⁻¹ aphidicolin, cells were elongated and nucleus-associated longitudinal MT bundles were formed, but the nuclear DNA contents did not exceed 4C and the nuclei did not elongate. These results indicate that an increase in the nuclear DNA content above 4C is also required for nuclear elongation.

Acute effect of carbamazepine on corticothalamic 5-9-Hz and thalamocortical spindle (10-16-Hz) oscillations in the rat.

Science.gov (United States)

Zheng, Thomas W; O'Brien, Terence J; Kulikova, Sofya P; Reid, Christopher A; Morris, Margaret J; Pinault, Didier

2014-03-01

A major side effect of carbamazepine (CBZ), a drug used to treat neurological and neuropsychiatric disorders, is drowsiness, a state characterized by increased slow-wave oscillations with the emergence of sleep spindles in the electroencephalogram (EEG). We conducted cortical EEG and thalamic cellular recordings in freely moving or lightly anesthetized rats to explore the impact of CBZ within the intact corticothalamic (CT)-thalamocortical (TC) network, more specifically on CT 5-9-Hz and TC spindle (10-16-Hz) oscillations. Two to three successive 5-9-Hz waves were followed by a spindle in the cortical EEG. A single systemic injection of CBZ (20 mg/kg) induced a significant increase in the power of EEG 5-9-Hz oscillations and spindles. Intracellular recordings of glutamatergic TC neurons revealed 5-9-Hz depolarizing wave-hyperpolarizing wave sequences prolonged by robust, rhythmic spindle-frequency hyperpolarizing waves. This hybrid sequence occurred during a slow hyperpolarizing trough, and was at least 10 times more frequent under the CBZ condition than under the control condition. The hyperpolarizing waves reversed at approximately -70 mV, and became depolarizing when recorded with KCl-filled intracellular micropipettes, indicating that they were GABAA receptor-mediated potentials. In neurons of the GABAergic thalamic reticular nucleus, the principal source of TC GABAergic inputs, CBZ augmented both the number and the duration of sequences of rhythmic spindle-frequency bursts of action potentials. This indicates that these GABAergic neurons are responsible for the generation of at least the spindle-frequency hyperpolarizing waves in TC neurons. In conclusion, CBZ potentiates GABAA receptor-mediated TC spindle oscillations. Furthermore, we propose that CT 5-9-Hz waves can trigger TC spindles. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Dynamic maintenance of asymmetric meiotic spindle position through Arp2/3 complex-driven cytoplasmic streaming in mouse oocytes

Science.gov (United States)

Yi, Kexi; Unruh, Jay R.; Deng, Manqi; Slaughter, Brian D.; Rubinstein, Boris; Li, Rong

2012-01-01

Mature mammalian oocytes are poised for the completion of second polar body extrusion upon fertilization by positioning the metaphase spindle in close proximity to an actomyosin-rich cortical cap. Loss of this spindle position asymmetry is often associated with poor oocyte quality and infertility 1–3. Here, we report a novel role for the Arp2/3 actin nucleation complex in the maintenance of asymmetric spindle position in mature mouse oocytes. The Arp2/3 complex localizes to the cortical cap in a Ran GTPase-dependent manner and accounts for the nucleation of the majority of actin filaments in both the cortical cap and a cytoplasmic actin network. Inhibition of Arp2/3 complex activity or localization leads to rapid dissociation of the spindle from the cortex. High resolution live imaging and spatiotemporal image correlation spectroscopy (STICS) analysis reveal that in normal oocytes actin filaments flow continuously away from the Arp2/3-rich cortex, generating a cytoplamic streaming that results in a net pushing force on the spindle toward the actomyosin cap. Arp2/3 inhibition not only diminishes this actin flow and cytoplamic streaming but also enables a reverse streaming driven by myosin-II-based cortical contraction, leading to spindle movement away from the cortex. We conclude that the Arp2/3 complex maintains asymmetric meiotic spindle position by generating an actin polymerization-driven cytoplamic streaming and by suppressing a counteracting force from myosin-II-based contractility. PMID:21874009

A Modeling approach for analysis and improvement of spindle-holder-tool assembly dynamics

OpenAIRE

Budak, Erhan; Ertürk, A.; Erturk, A.; Özgüven, H. N.; Ozguven, H. N.

2006-01-01

The most important information required for chatter stability analysis is the dynamics of the involved structures, i.e. the frequency response functions (FRFs) which are usually determined experimentally. In this study, the tool point FRF of a spindle-holder-tool assembly is analytically determined by using the receptance coupling and structural modification techniques. Timoshenko’s beam model is used for increased accuracy. The spindle is also modeled analytically with elastic supports repre...

E-cadherin is required for centrosome and spindle orientation in Drosophila male germline stem cells.

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Mayu Inaba

2010-08-01

Full Text Available Many adult stem cells reside in a special microenvironment known as the niche, where they receive essential signals that specify stem cell identity. Cell-cell adhesion mediated by cadherin and integrin plays a crucial role in maintaining stem cells within the niche. In Drosophila melanogaster, male germline stem cells (GSCs are attached to niche component cells (i.e., the hub via adherens junctions. The GSC centrosomes and spindle are oriented toward the hub-GSC junction, where E-cadherin-based adherens junctions are highly concentrated. For this reason, adherens junctions are thought to provide a polarity cue for GSCs to enable proper orientation of centrosomes and spindles, a critical step toward asymmetric stem cell division. However, understanding the role of E-cadherin in GSC polarity has been challenging, since GSCs carrying E-cadherin mutations are not maintained in the niche. Here, we tested whether E-cadherin is required for GSC polarity by expressing a dominant-negative form of E-cadherin. We found that E-cadherin is indeed required for polarizing GSCs toward the hub cells, an effect that may be mediated by Apc2. We also demonstrated that E-cadherin is required for the GSC centrosome orientation checkpoint, which prevents mitosis when centrosomes are not correctly oriented. We propose that E-cadherin orchestrates multiple aspects of stem cell behavior, including polarization of stem cells toward the stem cell-niche interface and adhesion of stem cells to the niche supporting cells.

Plant cell wall polysaccharide analysis during cell elongation

DEFF Research Database (Denmark)

Guo, Xiaoyuan

Plant cell walls are complex structures whose composition and architecture are important to various cellular activities. Plant cell elongation requires a high level of rearrangement of the cell wall polymers to enable cell expansion. However, the cell wall polysaccharides dynamics during plant cell...... elongation is poorly understood. This PhD project aims to elucidate the cell wall compositional and structural change during cell elongation by using Comprehensive Microarray Polymer Profiling (CoMPP), microscopic techniques and molecular modifications of cell wall polysaccharide. Developing cotton fibre......, pea and Arabidopsis thaliana were selected as research models to investigate different types of cell elongation, developmental elongation and tropism elongation. A set of comprehensive analysis covering 4 cotton species and 11 time points suggests that non-cellulosic polysaccharides contribute...

Spindle disturbances in human-hamster hybrid (AL) cells induced by mobile communication frequency range signals.

Science.gov (United States)

Schrader, Thorsten; Münter, Klaus; Kleine-Ostmann, Thomas; Schmid, Ernst

2008-12-01

The production of spindle disturbances in FC2 cells, a human-hamster hybrid (A(L)) cell line, by non-ionizing radiation was studied using an electromagnetic field with a field strength of 90 V/m at a frequency of 835 MHz. Due to the given experimental conditions slide flask cultures were exposed at room temperature in a microTEM (transversal electromagnetic field) cell, which allows optimal experimental conditions for small samples of biological material. Numerical calculations suggest that specific absorption rates of up to 60 mW/kg are reached for maximum field exposure. All exposure field parameters--either measured or calculable--are precisely defined and, for the first time, traceable to the standards of the SI system of physical units. Compared with co-incident negative controls, the results of two independently performed experiments suggest that exposure periods of time from 0.5 to 2 h with an electric field strength of 90 V/m are spindle acting agents as predominately indicated by the appearance of spindle disturbances at the ana- and telophase stages (especially lagging and non-disjunction of single chromosomes) of cell divisions. The spindle disturbances do not change the fraction of mitotic cells with increasing exposure time up to 2 h. Due to the applied experimental conditions an influence of temperature as a confounder parameter for spindle disturbances can be excluded.

SPINDLE: A 2-Stage Nuclear-Powered Cryobot for Ocean World Exploration

Science.gov (United States)

Stone, W.; Hogan, B.; Siegel, V. L.; Howe, T.; Howe, S.; Harman, J.; Richmond, K.; Flesher, C.; Clark, E.; Lelievre, S.; Moor, J.; Rothhammer, B.

2016-12-01

SPINDLE (Sub-glacial Polar Ice Navigation, Descent, and Lake Exploration) is a 2-stage autonomous vehicle system consisting of a robotic ice-penetrating carrier vehicle (cryobot) and a marsupial, hovering autonomous underwater vehicle (HAUV). The cryobot will descend through an ice body into a sub-ice aqueous environment and deploy the HAUV to conduct long range reconnaissance, life search, and sample collection. The HAUV will return to, and auto-dock with, the cryobot at the conclusion of the mission for subsequent data uplink and sample return to the surface. The SPINDLE cryobot has been currently designed for a 1.5 kilometer penetration through a terrestrial ice sheet and the HAUV has been designed for persistent exploration and science presence in for deployments up to a kilometer radius from the cryobot. Importantly, the cryobot is bi-directional and vertically controllable both in an ice sheet as well as following breakthrough into a subglacial water cavity / ocean. The vehicle has been designed for long-duration persistent science in subglacial cavities and to allow for subsequent return-to-surface at a much later date or subsequent season. Engineering designs for the current SPINDLE cryobot will be presented in addition to current designs for autonomous rendezvous, docking, and storing of the HAUV system into the cryobot for subsequent recovery of the entire system to the surface. Taken to completion in a three-phase program, SPINDLE will deliver an integrated and field-tested system that will be directly transferable into a Flagship-class mission to either the hypothesized shallow lakes of Europa, the sub-surface ocean of Ganymede, or the geyser/plume sources on both Europa and Enceladus. We present the results of several parallel laboratory investigations into advanced power transmission systems (laser, high voltage) as well as onboard systems that enable the SPINDLE vehicle to access any subglacial lake on earth while using non-nuclear surrogate, surface

Casein kinase II is required for the spindle assembly checkpoint by regulating Mad2p in fission yeast

Energy Technology Data Exchange (ETDEWEB)

Shimada, Midori [Department of Biochemistry and Cell Biology, Graduate School of Medicine, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Yamamoto, Ayumu [Department of Chemistry, Shizuoka University, 836 Ohya, Suruga-ku, Sizuoka 422-8529 (Japan); Murakami-Tonami, Yuko; Nakanishi, Makoto; Yoshida, Takashi [Department of Biochemistry and Cell Biology, Graduate School of Medicine, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Aiba, Hirofumi [Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464-8601 (Japan); Murakami, Hiroshi, E-mail: hmura@med.nagoya-cu.ac.jp [Department of Biochemistry and Cell Biology, Graduate School of Medicine, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan)

2009-10-23

The spindle checkpoint is a surveillance mechanism that ensures the fidelity of chromosome segregation in mitosis. Here we show that fission yeast casein kinase II (CK2) is required for this checkpoint function. In the CK2 mutants mitosis occurs in the presence of a spindle defect, and the spindle checkpoint protein Mad2p fails to localize to unattached kinetochores. The CK2 mutants are sensitive to the microtubule depolymerising drug thiabendazole, which is counteracted by ectopic expression of mad2{sup +}. The level of Mad2p is low in the CK2 mutants. These results suggest that CK2 has a role in the spindle checkpoint by regulating Mad2p.

Casein kinase II is required for the spindle assembly checkpoint by regulating Mad2p in fission yeast

International Nuclear Information System (INIS)

Shimada, Midori; Yamamoto, Ayumu; Murakami-Tonami, Yuko; Nakanishi, Makoto; Yoshida, Takashi; Aiba, Hirofumi; Murakami, Hiroshi

2009-01-01

The spindle checkpoint is a surveillance mechanism that ensures the fidelity of chromosome segregation in mitosis. Here we show that fission yeast casein kinase II (CK2) is required for this checkpoint function. In the CK2 mutants mitosis occurs in the presence of a spindle defect, and the spindle checkpoint protein Mad2p fails to localize to unattached kinetochores. The CK2 mutants are sensitive to the microtubule depolymerising drug thiabendazole, which is counteracted by ectopic expression of mad2 + . The level of Mad2p is low in the CK2 mutants. These results suggest that CK2 has a role in the spindle checkpoint by regulating Mad2p.

Translational Control of Cell Division by Elongator

Directory of Open Access Journals (Sweden)

Fanelie Bauer

2012-05-01

Full Text Available Elongator is required for the synthesis of the mcm5s2 modification found on tRNAs recognizing AA-ending codons. In order to obtain a global picture of the role of Elongator in translation, we used reverse protein arrays to screen the fission yeast proteome for translation defects. Unexpectedly, this revealed that Elongator inactivation mainly affected three specific functional groups including proteins implicated in cell division. The absence of Elongator results in a delay in mitosis onset and cytokinesis defects. We demonstrate that the kinase Cdr2, which is a central regulator of mitosis and cytokinesis, is under translational control by Elongator due to the Lysine codon usage bias of the cdr2 coding sequence. These findings uncover a mechanism by which the codon usage, coupled to tRNA modifications, fundamentally contributes to gene expression and cellular functions.

Phosphatase-regulated recruitment of the spindle- and kinetochore-associated (Ska complex to kinetochores

Directory of Open Access Journals (Sweden)

Sushama Sivakumar

2017-11-01

Full Text Available Kinetochores move chromosomes on dynamic spindle microtubules and regulate signaling of the spindle checkpoint. The spindle- and kinetochore-associated (Ska complex, a hexamer composed of two copies of Ska1, Ska2 and Ska3, has been implicated in both roles. Phosphorylation of kinetochore components by the well-studied mitotic kinases Cdk1, Aurora B, Plk1, Mps1, and Bub1 regulate chromosome movement and checkpoint signaling. Roles for the opposing phosphatases are more poorly defined. Recently, we showed that the C terminus of Ska1 recruits protein phosphatase 1 (PP1 to kinetochores. Here we show that PP1 and protein phosphatase 2A (PP2A both promote accumulation of Ska at kinetochores. Depletion of PP1 or PP2A by siRNA reduces Ska binding at kinetochores, impairs alignment of chromosomes to the spindle midplane, and causes metaphase delay or arrest, phenotypes that are also seen after depletion of Ska. Artificial tethering of PP1 to the outer kinetochore protein Nuf2 promotes Ska recruitment to kinetochores, and it reduces but does not fully rescue chromosome alignment and metaphase arrest defects seen after Ska depletion. We propose that Ska has multiple functions in promoting mitotic progression and that kinetochore-associated phosphatases function in a positive feedback cycle to reinforce Ska complex accumulation at kinetochores.

Relations between ultrastructure of mitotic spindle and chromosome translocation

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Jadwiga A. Tarkowska

2014-01-01

Full Text Available Dividing endosperm cells of Haemanthus katherinae Bak. treated with an 0.25 per cent mixture of water-soluble glycosides from Nerium oleander were insepected in a light microscope (LM and severe disturbances were found in all phases of mitosis. The same cells were observed in the electron microscope (EM and relations were noted and analysed between the chromosome arrangement and the submicroscopic structure of the mitotuc spindle. The successive steps in the disintegration of the formed spindle are described: fragmentatiun of all microtubules (MTs starting from the poles, disappearance of non-kinetachore MTs and further the external MTs of the kineto,chore bundle. The central (internal parallel ones remain the longest at the kinerf,ochares. Oleander glycosides cause disintegration of the existing MTs and prevent formation of new ones. The causes of restitution transformations in the successive phases of mitosis are discussed.

Trade studies of plasma elongation for next-step tokamaks

International Nuclear Information System (INIS)

Galambos, J.D.; Strickler, D.J.; Peng, Y.K.M.; Reid, R.L.

1988-09-01

The effect of elongation on minimum-cost devices is investigated for elongations ranging from 2 to 3. The analysis, carried out with the TETRA tokamak systems code, includes the effects of elongation on both physics (plasma beta limit) and engineering (poloidal field coil currents) issues. When ignition is required, the minimum cost occurs for elongations from 2.3 to 2.9, depending on the plasma energy confinement scaling used. Scalings that include favorable plasma current dependence and/or degradation with fusion power tend to have minimum cost at higher elongation (2.5-2.9); scalings that depend primarily on size result in lower elongation (/approximately/2.3) for minimum cost. For design concepts that include steady-state current-driven operation, minimum cost occurs at an elongation of 2.3. 12 refs., 13 figs

The Thermohydrodynamic Analysis of Sliding Bearing High-Speed Motorized Spindle by Rotor Dynamic

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Li Songsheng

2017-01-01

Full Text Available This is paper presents thermohydrodynamic characteristics of high speed motorized spindle sliding bearing rotor system. The dynamic characteristic of the oil film bearing is affected by temperature increment, thereby affecting the high-speed spindle rotor system dynamics. This study applied the hydrodynamic lubrication theory, the influence of temperature on the viscosity of lubricating oil, associated with the bearing stiffness, oil film damping and other performance parameters, is considered in generalized Reynolds equation of oil film bearing. The theoretical model of the sliding bearing rotor system is established by using the transfer matrix method to analyze the dynamic characteristic and verified by experiments. The results show the high temperature environment in the motorized spindle and the friction of the bearing lead to oil temperature rise and viscosity reduction, which influences the bearing capacity, stiffness and damping, hence impact on the critical speeds and modal shapes of the sliding bearing rotor system.

Sleep spindle alterations in patients with Parkinson's disease

DEFF Research Database (Denmark)

Christensen, Julie Anja Engelhard; Nikolic, Miki; Warby, Simon C.

2015-01-01

The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score...

Combined classical spindle cell/pleomorphic lipoma spectrum imaging and clinical data

Energy Technology Data Exchange (ETDEWEB)

Younan, Yara; Gonzalez, Felix; Umpierrez, Monica; Singer, Adam D. [Emory University Hospital, Department of Radiology and Imaging Sciences Section of Musculoskeletal Imaging, Atlanta, GA (United States); Martinez, Anthony; Edgar, Mark [Emory University Hospital, Department of Pathology, Atlanta, GA (United States); Reimer, Nickolas [Emory University Hospital, Department of Orthopedic Surgery, Atlanta, GA (United States); Subhawong, Ty [University of Miami, Department of Radiology, Miami, FL (United States)

2018-01-15

Compile the largest study to date on the imaging and clinical features of the classic spindle cell/pleomorphic lipoma spectrum and suggest this diagnosis be included in the differential for benign and malignant macroscopic fat-containing soft tissue masses regardless of the mass location or patient demographics. An institutional search was performed to identify all available classic-type spindle cell/pleomorphic lipomas with available demographic and imaging data. Images and reports were analyzed by one MSK-trained radiologist and radiographic, anatomic and clinical data were recorded. Additionally, a literature search was performed to identify studies describing the spindle cell lipoma spectrum imaging features and were combined with institutional data. Forty-two institutional cases were identified, 37 of which had MRIs performed among which 21 had images available (T1- and T2-weighted pulse sequences) for review while the remainder had outside reports detailing the mass imaging features. There was a mean age of 57 with 79% of cases occurring in males. Contrary to prior reports, 57% of masses were subcutaneous, and the neck and back region accounted for 26% of cases. When the institutional cases were combined with available data in the literature, there was a new sample size of 91 masses, 74 of which had MRI and/or CT data. Eighty-seven percent of masses were heterogeneous, 51% were composed of less than 75% fat, 65% were in the back, neck or shoulder region, 27% of masses were deep and 91% demonstrated enhancement. Eighty-two percent of patients were males with a mean age of 58 at excision. Imaging features, patient demographics and tumor location alone are not enough to differentiate tumors of the spindle cell lipoma spectrum from other macroscopic fat-containing benign and malignant tumors, and these entities should be included in the same imaging differential diagnosis. (orig.)

Lateralised sleep spindles relate to false memory generation.

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Shaw, John J; Monaghan, Padraic

2017-12-01

Sleep is known to enhance false memories: After presenting participants with lists of semantically related words, sleeping before recalling these words results in a greater acceptance of unseen "lure" words related in theme to previously seen words. Furthermore, the right hemisphere (RH) seems to be more prone to false memories than the left hemisphere (LH). In the current study, we investigated the sleep architecture associated with these false memory and lateralisation effects in a nap study. Participants viewed lists of related words, then stayed awake or slept for approximately 90min, and were then tested for recognition of previously seen-old, unseen-new, or unseen-lure words presented either to the LH or RH. Sleep increased acceptance of unseen-lure words as previously seen compared to the wake group, particularly for RH presentations of word lists. RH lateralised stage 2 sleep spindle density relative to the LH correlated with this increase in false memories, suggesting that RH sleep spindles enhanced false memories in the RH. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cenp-meta is required for sustained spindle checkpoint

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Thomas Rubin

2014-05-01

Full Text Available Cenp-E is a kinesin-like motor protein required for efficient end-on attachment of kinetochores to the spindle microtubules. Cenp-E immunodepletion in Xenopus mitotic extracts results in the loss of mitotic arrest and massive chromosome missegregation, whereas its depletion in mammalian cells leads to chromosome segregation defects despite the presence of a functional spindle assembly checkpoint (SAC. Cenp-meta has previously been reported to be the Drosophila homolog of vertebrate Cenp-E. In this study, we show that cenp-metaΔ mutant neuroblasts arrest in mitosis when treated with colchicine. cenp-metaΔ mutant cells display a mitotic delay. Yet, despite the persistence of the two checkpoint proteins Mad2 and BubR1 on unattached kinetochores, these cells eventually enter anaphase and give rise to highly aneuploid daughter cells. Indeed, we find that cenp-metaΔ mutant cells display a slow but continuous degradation of cyclin B, which eventually triggers the mitotic exit observed. Thus, our data provide evidence for a role of Cenp-meta in sustaining the SAC response.

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

In-situ hot corrosion testing of candidate materials for exhaust valve spindles

DEFF Research Database (Denmark)

Bihlet, Uffe; Hoeg, Harro A.; Dahl, Kristian Vinter

2011-01-01

The two stroke diesel engine has been continually optimized since its invention more than a century ago. One of the ways to increase fuel efficiency further is to increase the compression ratio, and thereby the temperature in the combustion chamber. Because of this, and the composition of the fuel...... used, exhaust valve spindles in marine diesel engines are subjected to high temperatures and stresses as well as molten salt induced corrosion. To investigate candidate materials for future designs which will involve the HIP process, a spindle with Ni superalloy material samples inserted in a HIPd Ni49...

Dynamics modeling and modal experimental study of high speed motorized spindle

International Nuclear Information System (INIS)

Li, Yunsong; Chen, Xiaoan; Zhang, Peng; Zhou, Jinming

2017-01-01

This paper presents a dynamical model of high speed motorized spindles in free state and work state. In the free state, the housing is modeled as a rotor with equivalent masses including bearing pedestals, motor stator and rear end cover. As a consequence, a double rotor dynamics can be modeled for high speed motorized spindles by a bearing element which connects the housing and bearing pedestals. In the work state, the housing is fixed and the system becomes a bearing-rotor dynamical model. An excitation-measurement test in the free state is designed to analyze the cross spectral density and auto spectral density of input and output signals. Then the frequency response function of system and coherence function of input and output signals which are used to analyze the inherent characteristics of the double- rotor model can be obtained. The other vibration test in the work state is designed to research the dynamical supporting characteristics of bearings and the effects from bearings on the inherent characteristics of the system. The good agreement between the experimental data and theoretical results indicates that the dynamical model in two states is capable of accurately predicting the dynamic behavior of high speed motorized spindles

Dynamics modeling and modal experimental study of high speed motorized spindle

Energy Technology Data Exchange (ETDEWEB)

Li, Yunsong; Chen, Xiaoan; Zhang, Peng; Zhou, Jinming [Chongqing Univ., Chongqing (China)

2017-03-15

This paper presents a dynamical model of high speed motorized spindles in free state and work state. In the free state, the housing is modeled as a rotor with equivalent masses including bearing pedestals, motor stator and rear end cover. As a consequence, a double rotor dynamics can be modeled for high speed motorized spindles by a bearing element which connects the housing and bearing pedestals. In the work state, the housing is fixed and the system becomes a bearing-rotor dynamical model. An excitation-measurement test in the free state is designed to analyze the cross spectral density and auto spectral density of input and output signals. Then the frequency response function of system and coherence function of input and output signals which are used to analyze the inherent characteristics of the double- rotor model can be obtained. The other vibration test in the work state is designed to research the dynamical supporting characteristics of bearings and the effects from bearings on the inherent characteristics of the system. The good agreement between the experimental data and theoretical results indicates that the dynamical model in two states is capable of accurately predicting the dynamic behavior of high speed motorized spindles.

IL-6 and mouse oocyte spindle.

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Jashoman Banerjee

Full Text Available Interleukin 6 (IL-6 is considered a major indicator of the acute-phase inflammatory response. Endometriosis and pelvic inflammation, diseases that manifest elevated levels of IL-6, are commonly associated with higher infertility. However, the mechanistic link between elevated levels of IL-6 and poor oocyte quality is still unclear. In this work, we explored the direct role of this cytokine as a possible mediator for impaired oocyte spindle and chromosomal structure, which is a critical hurdle in the management of infertility. Metaphase-II mouse oocytes were exposed to recombinant mouse IL-6 (50, 100 and 200 ng/mL for 30 minutes and subjected to indirect immunofluorescent staining to identify alterations in the microtubule and chromosomal alignment compared to untreated controls. The deterioration in microtubule and chromosomal alignment were evaluated utilizing both fluorescence and confocal microscopy, and were quantitated with a previously reported scoring system. Our results showed that IL-6 caused a dose-dependent deterioration in microtubule and chromosomal alignment in the treated oocytes as compared to the untreated group. Indeed, IL-6 at a concentration as low as 50 ng/mL caused deterioration in the spindle structure in 60% of the oocytes, which increased significantly (P<0.0001 as IL-6 concentration was increased. In conclusion, elevated levels of IL-6 associated with endometriosis and pelvic inflammation may reduce the fertilizing capacity of human oocyte through a mechanism that involves impairment of the microtubule and chromosomal structure.

Gas flow through the clearances of screw spindle vacuum pumps; Gasspaltstroemungen in Schraubenspindel-Vakuumpumpen

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Kauder, K.; Wenderott, D. [Dortmund Univ. (Germany). FG Fluidenergiemaschinen

1998-12-31

The documentation `Schraubenmaschinen` deals with the subject `screw spindle vacuum pump` for the first time. Therefore, this paper presents the type of maschine `screw spindle vacuum pump`, fixes its limits to the better known screw type compressor and finally classifies it in the crossover of vacuum-technology, characteristic geometry and the numerical simulation. The suggested reflections to choose a proper model of flow are based on the geometry of the screw spindle vacuum pump and fundamentals concerning the vacuum-technology and the state of flow. (orig.) [Deutsch] Die Schriftenreihe `Schraubenmaschinen` behandelt erstmals das Thema `Schraubenspindel-Vakuumpumpe`. Aus diesem Grund stellt der vorliegende Beitrag den Maschinentyp Schraubenspindel-Vakuumpumpe vor, grenzt ihn zur bekannteren Schraubenmaschine ab und ordnet ihn in der Schnittmenge aus Vakuumtechnik, charakteristischer Maschinengeometrie und der Simulation ein. Auf den vakuumtechnischen und stroemungstechnischen Grundlagen sowie geometrischen Betrachtungen basieren die genannten Ueberlegungen zur Auswahl geeigneter Stroemungsmodelle. (orig.)

Research on a power management system for thermoelectric generators to drive wireless sensors on a spindle unit.

Science.gov (United States)

Li, Sheng; Yao, Xinhua; Fu, Jianzhong

2014-07-16

Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles.

Science.gov (United States)

Carrasco, Dario I; Vincent, Jacob A; Cope, Timothy C

2017-04-01

Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP) and tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. The NaV 1.6 isoform was selected for both its capacity to produce INaP and for its presence in other mechanosensors that fire tonically. The present study shows that NaV 1.6 immunoreactivity (IR) is concentrated in heminodes, presumably where tonic firing is generated, and we were surprised to find NaV 1.6 IR strongly expressed also in the sensory terminals, where mechanotransduction occurs. This spatial pattern of NaV 1.6 IR distribution was consistent for three mammalian species (rat, cat, and mouse), as was tonic firing by primary spindle afferents. These findings meet some of the conditions needed to establish participation of INaP in tonic firing by primary sensory endings. The study was extended to two additional NaV isoforms, selected for their sensitivity to TTX, excluding TTX-resistant NaV channels, which alone are insufficient to support firing by primary spindle endings. Positive immunoreactivity was found for NaV 1.1 , predominantly in sensory terminals together with NaV 1.6 and for NaV 1.7 , mainly in preterminal axons. Differential distribution in primary sensory endings suggests specialized roles for these three NaV isoforms in the process of mechanosensory signaling by muscle spindles. NEW & NOTEWORTHY The molecular mechanisms underlying mechanosensory signaling responsible for proprioceptive functions are not completely elucidated. This study provides the first evidence that voltage-gated sodium channels (NaVs) are expressed in the spindle primary sensory ending, where NaVs are found at every site

Nicotine-induced Disturbances of Meiotic Maturation in Cultured Mouse Oocytes: Alterations of Spindle Integrity and Chromosome Alignment

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Zenzes Maria

2004-09-01

Full Text Available Abstract We investigated whether nicotine exposure in vitro of mouse oocytes affects spindle and chromosome function during meiotic maturation (M-I and M-II. Oocytes in germinal vesicle (GV stage were cultured in nicotine for 8 h or for 16 h, to assess effects in M-I and in metaphase II (M-II. The latter culture setting used the three protocols: 8 h nicotine then 8 h medium (8N + 8M; 16 h nicotine (16N; 8 h medium then 8 h nicotine (8M + 8N. Non-toxic concentrations of nicotine at 1.0, 2.5, 5.0 and 10.0 mmol/L were used. Spindle-chromosome configurations were analyzed with wide-field optical sectioning microscopy. In 8 h cultures, nicotine exposure resulted in dose-related increased proportions of M-I oocytes with defective spindle-chromosome configurations. A dose-related delayed entry into anaphase I was also detected. In 16 h cultures, nicotine exposure for the first 8 h (8N + 8M, or for 16 h (16N, resulted in dose- and time-related increased proportions of oocytes arrested in M-I (10 mmol/L; 8 h: 53.2%, controls 9.6%; 16 h: 87.6%, controls 8.5%. Defects in M-I spindles and chromosomes caused M-I arrest leading to dose-related decreased proportions of oocytes that reached metaphase-II (10 mmol/L 8 h: 46.8%, controls 90.4%;16 h: 12.4%, controls 91.5%. A delayed anaphase-I affected the normal timing of M-II, leading to abnormal oocytes with dispersed chromosomes, or with double spindles and no polar body. Nicotine exposure during the second 8 h (8M + 8N resulted in dose-related, increased proportions of M-II oocytes with defective spindles and chromosomes (10 mmol/L: 42.9%, controls 2.0%. Nicotine has no adverse effects on GV break down, but induces spindle and chromosome defects compromising oocyte meiotic maturation and development.

Nek2A destruction marks APC/C activation at the prophase-to-prometaphase transition by spindle-checkpoint-restricted Cdc20.

Science.gov (United States)

Boekhout, Michiel; Wolthuis, Rob

2015-04-15

Nek2 isoform A (Nek2A) is a presumed substrate of the anaphase-promoting complex/cyclosome containing Cdc20 (APC/C(Cdc20)). Nek2A, like cyclin A, is degraded in mitosis while the spindle checkpoint is active. Cyclin A prevents spindle checkpoint proteins from binding to Cdc20 and is recruited to the APC/C in prometaphase. We found that Nek2A and cyclin A avoid being stabilized by the spindle checkpoint in different ways. First, enhancing mitotic checkpoint complex (MCC) formation by nocodazole treatment inhibited the degradation of geminin and cyclin A, whereas Nek2A disappeared at a normal rate. Second, depleting Cdc20 effectively stabilized cyclin A but not Nek2A. Nevertheless, Nek2A destruction crucially depended on Cdc20 binding to the APC/C. Third, in contrast to cyclin A, Nek2A was recruited to the APC/C before the start of mitosis. Interestingly, the spindle checkpoint very effectively stabilized an APC/C-binding mutant of Nek2A, which required the Nek2A KEN box. Apparently, in cells, the spindle checkpoint primarily prevents Cdc20 from binding destruction motifs. Nek2A disappearance marks the prophase-to-prometaphase transition, when Cdc20, regardless of the spindle checkpoint, activates the APC/C. However, Mad2 depletion accelerated Nek2A destruction, showing that spindle checkpoint release further increases APC/C(Cdc20) catalytic activity. © 2015. Published by The Company of Biologists Ltd.

Inhibition of clathrin by pitstop 2 activates the spindle assembly checkpoint and induces cell death in dividing HeLa cancer cells

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Smith Charlotte M

2013-01-01

Full Text Available Abstract Background During metaphase clathrin stabilises the mitotic spindle kinetochore(K-fibres. Many anti-mitotic compounds target microtubule dynamics. Pitstop 2™ is the first small molecule inhibitor of clathrin terminal domain and inhibits clathrin-mediated endocytosis. We investigated its effects on a second function for clathrin in mitosis. Results Pitstop 2 did not impair clathrin recruitment to the spindle but disrupted its function once stationed there. Pitstop 2 trapped HeLa cells in metaphase through loss of mitotic spindle integrity and activation of the spindle assembly checkpoint, phenocopying clathrin depletion and aurora A kinase inhibition. Conclusions Pitstop 2 is therefore a new tool for investigating clathrin spindle dynamics. Pitstop 2 reduced viability in dividing HeLa cells, without affecting dividing non-cancerous NIH3T3 cells, suggesting that clathrin is a possible novel anti-mitotic drug target.

ATFL elongation after Brostrom procedure: a biomechanical investigation.

Science.gov (United States)

Kirk, Kevin L; Campbell, John T; Guyton, Gregory P; Parks, Brent G; Schon, Lew C

2008-11-01

Elongation of ligaments during early mobilization after reconstruction may be associated with decreased stability. We evaluated elongation of the anterior talofibular ligament (ATFL) before and after lateral ligament reconstruction within a physiologic range of motion with protected and unprotected, isolated dorsiflexion/plantarflexion range of motion. Six fresh frozen cadaver legs were used with the ATFL meticulously dissected. A differential variable reluctance transducer (DVRT) was spaced to span the course of the ATFL using consistent placement points based on previous reports. Elongation was measured in a load frame with protected motion of 30 degrees plantarflexion and 10 degrees dorsiflexion for the intact and sectioned ATFL and for the repaired specimen with and without protected motion. The proximal DVRT anchor point was detached for sectioning and repair of the ATFL and replaced at the same position. Testing was 1000 cycles at 1 Hz for the repaired protected specimen and 10 cycles at 1 Hz for all other stages. Initial elongation in the unprotected, repaired group was significantly higher than initial elongation in the intact (p ankle after lateral ankle ligament reconstruction was not associated with elongation of the ATFL. The ATFL elongated significantly by comparison without protected dorsiflexion/plantarflexion. The study provides biomechanical support for the safety of early protected dorsiflexion/plantarflexion range of motion after Broström reconstruction.

Glucose assisted synthesis of hollow spindle LiMnPO_4/C nanocomposites for high performance Li-ion batteries

International Nuclear Information System (INIS)

Fu, Xiaoning; Chang, Zhaorong; Chang, Kun; Li, Bao; Tang, Hongwei; Shangguan, Enbo; Yuan, Xiao-Zi; Wang, Haijiang

2015-01-01

Graphical abstract: Nano-sized hollow spindle LiMnPO_4 with a well-developed olivine-type structure exhibits a high specific capacity and cycling performance. - Highlights: • A pure and well-crystallized LiMnPO_4 are synthesized via a solution-phase method. • The LiMnPO_4/C composite constitutes highly and uniformly distributed hollow spindles. • The LiMnPO_4/C composite exhibits a high specific capacity and cycling performance. • The growth process of the hollow spindle LiMnPO_4 particles is revealed. - Abstract: Nano-sized hollow spindle LiMnPO_4 with a well-developed olivine-type structure was synthesized with the assistance of glucose in dimethyl sulfoxide (DMSO)/H_2O under ambient pressure and 108 °C. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) images show that the LiMnPO_4 particles consist of hollow spindles with a mean width of 200 nm, length of 500-700 nm, and wall thickness of about 30-60 nm. The LiMnPO_4/C nanocomposite was obtained by sintering nano-sized LiMnPO_4 with glucose at 650 °C under an inert atmosphere for 4 h. With a coated carbon thickness of about 10 nm, the obtained composite maintained the morphology and size of the hollow spindle. The electrochemical tests show the specific capacity of LiMnPO_4/C nanocomposite is 161.8 mAh g"−"1 at 0.05C, 137.7 mAh g"−"1 at 0.1C and 110.8 mAh g"−"1 at 0.2 C. The retention of discharge capacity maintains 92% after 100 cycles at 0.2 C. After different rate cycles the high capacity of the LiMnPO_4/C nanocomposite can be recovered. This high performance is attributed to the composite material's hollow spindle structure, which facilitates the electrolyte infiltration, resulting in an increased solid-liquid interface. The carbon layer covering the hollow spindle also contributes to the high performance of the LiMnPO_4/C material as the carbon layer improves its electronic conductivity and the nano-scaled wall thickness decreases the paths of Li

Primary histiocytic sarcoma arising in the head and neck with predominant spindle cell component

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Zhao XF

2007-02-01

Full Text Available Abstract This is the first case report of Histiocytic Sarcoma (HS with predominant spindle cell component occurring in the head and neck region of a 41-year-old man. The tumor was composed of sheets of large round to oval cells with pleomorphic vesicular nuclei, prominent nucleoli and abundant eosinophilic cytoplasm. Multinucleated forms, numerous mitoses, and tumor necrosis were also noted. Sheets, fascicles, and whorls of spindle cells with spindled to ovoid vesicular nuclei, small to medium-sized distinct nucleoli, and eosinophilic cytoplasm were frequently observed. Immunohistochemical staining in the tumor cells was positive for CD163, CD68, lysozyme, CD45, and NSE. Focal expression of CD4 and S-100 was also noted. Electron microscopy demonstrated an abundance of lysosomes in the cytoplasm of tumor cells. Chromosome study revealed a 57–80 hyperdiploid [7]/46, XY [13] karyotype, including 3 to 4 copies of various chromosomes. The immunohistochemical and ultrastructural findings confirmed the diagnosis of HS.

Mitotic Spindle Asymmetry: A Wnt/PCP-Regulated Mechanism Generating Asymmetrical Division in Cortical Precursors

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Delphine Delaunay

2014-01-01

Full Text Available The regulation of asymmetric cell division (ACD during corticogenesis is incompletely understood. We document that spindle-size asymmetry (SSA between the two poles occurs during corticogenesis and parallels ACD. SSA appears at metaphase and is maintained throughout division, and we show it is necessary for proper neurogenesis. Imaging of spindle behavior and division outcome reveals that neurons preferentially arise from the larger-spindle pole. Mechanistically, SSA magnitude is controlled by Wnt7a and Vangl2, both members of the Wnt/planar cell polarity (PCP-signaling pathway, and relayed to the cell cortex by P-ERM proteins. In vivo, Vangl2 and P-ERM downregulation promotes early cell-cycle exit and prevents the proper generation of late-born neurons. Thus, SSA is a core component of ACD that is conserved in invertebrates and vertebrates and plays a key role in the tight spatiotemporal control of self-renewal and differentiation during mammalian corticogenesis.

Zwint-1 is required for spindle assembly checkpoint function and kinetochore-microtubule attachment during oocyte meiosis.

Science.gov (United States)

Woo Seo, Dong; Yeop You, Seung; Chung, Woo-Jae; Cho, Dong-Hyung; Kim, Jae-Sung; Su Oh, Jeong

2015-10-21

The key step for faithful chromosome segregation during meiosis is kinetochore assembly. Defects in this process result in aneuploidy, leading to miscarriages, infertility and various birth defects. However, the roles of kinetochores in homologous chromosome segregation during meiosis are ill-defined. Here we found that Zwint-1 is required for homologous chromosome segregation during meiosis. Knockdown of Zwint-1 accelerated the first meiosis by abrogating the kinetochore recruitment of Mad2, leading to chromosome misalignment and a high incidence of aneuploidy. Although Zwint-1 knockdown did not affect Aurora C kinase activity, the meiotic defects following Zwint-1 knockdown were similar to those observed with ZM447439 treatment. Importantly, the chromosome misalignment following Aurora C kinase inhibition was not restored after removing the inhibitor in Zwint-1-knockdown oocytes, whereas the defect was rescued after the inhibitor washout in the control oocytes. These results suggest that Aurora C kinase-mediated correction of erroneous kinetochore-microtubule attachment is primarily regulated by Zwint-1. Our results provide the first evidence that Zwint-1 is required to correct erroneous kinetochore-microtubule attachment and regulate spindle checkpoint function during meiosis.

Stability of tokamaks with elongated cross section

International Nuclear Information System (INIS)

An, C.H.; Bateman, G.

1978-08-01

Fixed boundary n = 1 MHD instabilities are studied computationally as a function of diamagnetism (β/sub pol/) and current profile in elongated toroidal equilibria (1 2) or a diamagnetic plasma (β/sub pol/ > 1) with only a mildly elongated cross section

Interplay between microtubule bundling and sorting factors ensures acentriolar spindle stability during C. elegans oocyte meiosis.

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Timothy J Mullen

2017-09-01

Full Text Available In many species, oocyte meiosis is carried out in the absence of centrioles. As a result, microtubule organization, spindle assembly, and chromosome segregation proceed by unique mechanisms. Here, we report insights into the principles underlying this specialized form of cell division, through studies of C. elegans KLP-15 and KLP-16, two highly homologous members of the kinesin-14 family of minus-end-directed kinesins. These proteins localize to the acentriolar oocyte spindle and promote microtubule bundling during spindle assembly; following KLP-15/16 depletion, microtubule bundles form but then collapse into a disorganized array. Surprisingly, despite this defect we found that during anaphase, microtubules are able to reorganize into a bundled array that facilitates chromosome segregation. This phenotype therefore enabled us to identify factors promoting microtubule organization during anaphase, whose contributions are normally undetectable in wild-type worms; we found that SPD-1 (PRC1 bundles microtubules and KLP-18 (kinesin-12 likely sorts those bundles into a functional orientation capable of mediating chromosome segregation. Therefore, our studies have revealed an interplay between distinct mechanisms that together promote spindle formation and chromosome segregation in the absence of structural cues such as centrioles.

Spindle-like thalamocortical synchronization in a rat brain slice preparation.

Science.gov (United States)

Tancredi, V; Biagini, G; D'Antuono, M; Louvel, J; Pumain, R; Avoli, M

2000-08-01

We obtained rat brain slices (550-650 microm) that contained part of the frontoparietal cortex along with a portion of the thalamic ventrobasal complex (VB) and of the reticular nucleus (RTN). Maintained reciprocal thalamocortical connectivity was demonstrated by VB stimulation, which elicited orthodromic and antidromic responses in the cortex, along with re-entry of thalamocortical firing originating in VB neurons excited by cortical output activity. In addition, orthodromic responses were recorded in VB and RTN following stimuli delivered in the cortex. Spontaneous and stimulus-induced coherent rhythmic oscillations (duration = 0.4-3.5 s; frequency = 9-16 Hz) occurred in cortex, VB, and RTN during application of medium containing low concentrations of the K(+) channel blocker 4-aminopyridine (0.5-1 microM). This activity, which resembled electroencephalograph (EEG) spindles recorded in vivo, disappeared in both cortex and thalamus during application of the excitatory amino acid receptor antagonist kynurenic acid in VB (n = 6). By contrast, cortical application of kynurenic acid (n = 4) abolished spindle-like oscillations at this site, but not those recorded in VB, where their frequency was higher than under control conditions. Our findings demonstrate the preservation of reciprocally interconnected cortical and thalamic neuron networks that generate thalamocortical spindle-like oscillations in an in vitro rat brain slice. As shown in intact animals, these oscillations originate in the thalamus where they are presumably caused by interactions between RTN and VB neurons. We propose that this preparation may help to analyze thalamocortical synchronization and to understand the physiopathogenesis of absence attacks.

High n ballooning modes in highly elongated tokamaks

International Nuclear Information System (INIS)

An, C.H.; Bateman, G.

1980-02-01

An analytic study of stability against high n ballooning modes in highly elongated axisymmetric plasmas is presented and compared with computational results. From the equation for the marginal pressure gradient, it is found that the local shear plays an important role on the stability of elongated and shifted plasma, and that high elongation deteriorates the stability by decreasing the stabilizing effects of field line bending and local shear. The net contribution of the local shear to stability decreases with elongation and shift for strongly ballooning modes (eigenfunctions strongly localized near the outer edge of the toroidal flux surfaces) but increases for interchange modes (eigenfunctions more uniform along the flux surfaces). The computational study of high n ballooning modes in a highly elongated plasma reveals that lowering the aspect ratio and broadening the pressure profile enhance the marginal beta for β/sub p/ less than unity but severely reduce the marginal beta for β/sub p/ larger than unity

Sleep spindle and K-complex detection using tunable Q-factor wavelet transform and morphological component analysis

Directory of Open Access Journals (Sweden)

Tarek eLajnef

2015-07-01

Full Text Available A novel framework for joint detection of sleep spindles and K-complex events, two hallmarks of sleep stage S2, is proposed. Sleep electroencephalography (EEG signals are split into oscillatory (spindles and transient (K-complex components. This decomposition is conveniently achieved by applying morphological component analysis (MCA to a sparse representation of EEG segments obtained by the recently introduced discrete tunable Q-factor wavelet transform (TQWT. Tuning the Q-factor provides a convenient and elegant tool to naturally decompose the signal into an oscillatory and a transient component. The actual detection step relies on thresholding (i the transient component to reveal K-complexes and (ii the time-frequency representation of the oscillatory component to identify sleep spindles. Optimal thresholds are derived from ROC-like curves (sensitivity versus FDR on training sets and the performance of the method is assessed on test data sets. We assessed the performance of our method using full-night sleep EEG data we collected from 14 participants. In comparison to visual scoring (Expert 1, the proposed method detected spindles with a sensitivity of 83.18% and false discovery rate (FDR of 39%, while K-complexes were detected with a sensitivity of 81.57% and an FDR of 29.54%. Similar performances were obtained when using a second expert as benchmark. In addition, when the TQWT and MCA steps were excluded from the pipeline the detection sensitivities dropped down to 70% for spindles and to 76.97% for K-complexes, while the FDR rose up to 43.62% and 49.09% respectively. Finally, we also evaluated the performance of the proposed method on a set of publicly available sleep EEG recordings. Overall, the results we obtained suggest that the TQWT-MCA method may be a valuable alternative to existing spindle and K-complex detection methods. Paths for improvements and further validations with large-scale standard open-access benchmarking data sets are

A Balance between Nuclear and Cytoplasmic Volumes Controls Spindle Length

Czech Academy of Sciences Publication Activity Database

Nováková, Lucia; Kovačovicová, Kristina; Dang-Nguyen, T.; Šodek, Martin; Škultéty, M.; Anger, Martin

2016-01-01

Roč. 11, č. 2 (2016), e0149535-e0149535 E-ISSN 1932-6203 R&D Projects: GA ČR GAP502/12/2201 Institutional support: RVO:67985904 Keywords : mitotoc spindle * size * cells Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.806, year: 2016

Regulation of mitotic spindle formation by the RhoA guanine nucleotide exchange factor ARHGEF10

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Satoh Takaya

2009-07-01

Full Text Available Abstract Background The Dbl family guanine nucleotide exchange factor ARHGEF10 was originally identified as the product of the gene associated with slowed nerve-conduction velocities of peripheral nerves. However, the function of ARHGEF10 in mammalian cells is totally unknown at a molecular level. ARHGEF10 contains no distinctive functional domains except for tandem Dbl homology-pleckstrin homology and putative transmembrane domains. Results Here we show that RhoA is a substrate for ARHGEF10. In both G1/S and M phases, ARHGEF10 was localized in the centrosome in adenocarcinoma HeLa cells. Furthermore, RNA interference-based knockdown of ARHGEF10 resulted in multipolar spindle formation in M phase. Each spindle pole seems to contain a centrosome consisting of two centrioles and the pericentriolar material. Downregulation of RhoA elicited similar phenotypes, and aberrant mitotic spindle formation following ARHGEF10 knockdown was rescued by ectopic expression of constitutively activated RhoA. Multinucleated cells were not increased upon ARHGEF10 knockdown in contrast to treatment with Y-27632, a specific pharmacological inhibitor for the RhoA effector kinase ROCK, which induced not only multipolar spindle formation, but also multinucleation. Therefore, unregulated centrosome duplication rather than aberration in cytokinesis may be responsible for ARHGEF10 knockdown-dependent multipolar spindle formation. We further isolated the kinesin-like motor protein KIF3B as a binding partner of ARHGEF10. Knockdown of KIF3B again caused multipolar spindle phenotypes. The supernumerary centrosome phenotype was also observed in S phase-arrested osteosarcoma U2OS cells when the expression of ARHGEF10, RhoA or KIF3B was abrogated by RNA interference. Conclusion Collectively, our results suggest that a novel RhoA-dependent signaling pathway under the control of ARHGEF10 has a pivotal role in the regulation of the cell division cycle. This pathway is not involved in

Mechanisms for focusing mitotic spindle poles by minus end-directed motor proteins.

Science.gov (United States)

Goshima, Gohta; Nédélec, François; Vale, Ronald D

2005-10-24

During the formation of the metaphase spindle in animal somatic cells, kinetochore microtubule bundles (K fibers) are often disconnected from centrosomes, because they are released from centrosomes or directly generated from chromosomes. To create the tightly focused, diamond-shaped appearance of the bipolar spindle, K fibers need to be interconnected with centrosomal microtubules (C-MTs) by minus end-directed motor proteins. Here, we have characterized the roles of two minus end-directed motors, dynein and Ncd, in such processes in Drosophila S2 cells using RNA interference and high resolution microscopy. Even though these two motors have overlapping functions, we show that Ncd is primarily responsible for focusing K fibers, whereas dynein has a dominant function in transporting K fibers to the centrosomes. We also report a novel localization of Ncd to the growing tips of C-MTs, which we show is mediated by the plus end-tracking protein, EB1. Computer modeling of the K fiber focusing process suggests that the plus end localization of Ncd could facilitate the capture and transport of K fibers along C-MTs. From these results and simulations, we propose a model on how two minus end-directed motors cooperate to ensure spindle pole coalescence during mitosis.

v-Src causes delocalization of Mklp1, Aurora B, and INCENP from the spindle midzone during cytokinesis failure

Energy Technology Data Exchange (ETDEWEB)

Soeda, Shuhei [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Nakayama, Yuji, E-mail: nakayama@mb.kyoto-phu.ac.jp [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414 (Japan); Honda, Takuya; Aoki, Azumi; Tamura, Naoki; Abe, Kohei; Fukumoto, Yasunori [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Yamaguchi, Naoto, E-mail: nyama@faculty.chiba-u.jp [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan)

2013-06-10

Src-family tyrosine kinases are aberrantly activated in cancers, and this activation is associated with malignant tumor progression. v-Src, encoded by the v-src transforming gene of the Rous sarcoma virus, is a mutant variant of the cellular proto-oncogene c-Src. Although investigations with temperature sensitive mutants of v-Src have shown that v-Src induces many oncogenic processes, the effects on cell division are unknown. Here, we show that v-Src inhibits cellular proliferation of HCT116, HeLa S3 and NIH3T3 cells. Flow cytometry analysis indicated that inducible expression of v-Src results in an accumulation of 4N cells. Time-lapse analysis revealed that binucleation is induced through the inhibition of cytokinesis, a final step of cell division. The localization of Mklp1, which is essential for cytokinesis, to the spindle midzone is inhibited in v-Src-expressing cells. Intriguingly, Aurora B, which regulates Mklp1 localization at the midzone, is delocalized from the spindle midzone and the midbody but not from the metaphase chromosomes upon v-Src expression. Mklp2, which is responsible for the relocation of Aurora B from the metaphase chromosomes to the spindle midzone, is also lost from the spindle midzone. These results suggest that v-Src inhibits cytokinesis through the delocalization of Mklp1 and Aurora B from the spindle midzone, resulting in binucleation. -- Highlights: • v-Src inhibits cell proliferation of HCT116, HeLa S3 and NIH3T3 cells. • v-Src induces binucleation together with cytokinesis failure. • v-Src causes delocalization of Mklp1, Aurora B and INCENP from the spindle midzone.

Structures of actin-like ParM filaments show architecture of plasmid-segregating spindles.

Science.gov (United States)

Bharat, Tanmay A M; Murshudov, Garib N; Sachse, Carsten; Löwe, Jan

2015-07-02

Active segregation of Escherichia coli low-copy-number plasmid R1 involves formation of a bipolar spindle made of left-handed double-helical actin-like ParM filaments. ParR links the filaments with centromeric parC plasmid DNA, while facilitating the addition of subunits to ParM filaments. Growing ParMRC spindles push sister plasmids to the cell poles. Here, using modern electron cryomicroscopy methods, we investigate the structures and arrangements of ParM filaments in vitro and in cells, revealing at near-atomic resolution how subunits and filaments come together to produce the simplest known mitotic machinery. To understand the mechanism of dynamic instability, we determine structures of ParM filaments in different nucleotide states. The structure of filaments bound to the ATP analogue AMPPNP is determined at 4.3 Å resolution and refined. The ParM filament structure shows strong longitudinal interfaces and weaker lateral interactions. Also using electron cryomicroscopy, we reconstruct ParM doublets forming antiparallel spindles. Finally, with whole-cell electron cryotomography, we show that doublets are abundant in bacterial cells containing low-copy-number plasmids with the ParMRC locus, leading to an asynchronous model of R1 plasmid segregation.

Axial length elongation in adults with long-standing unilateral traumatic cataract

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Jonel Steffen

2016-09-01

Full Text Available Background: Unilateral eye elongation with resultant axial myopia has been reported to occur secondary to visual deprivation from birth or early childhood. Acquired axial length elongation secondary to visual deprivation in adults has rarely been reported. Aim: To report acquired axial myopia in adults with visual deprivation due to long-standing unilateral traumatic cataract. Methods: Eleven consecutive adult patients who presented for cataract surgery with unilateral, long-standing, mature, traumatic cataracts and an interocular axial length difference of more than 1 mm were studied. Patients with a post-operative best corrected visual acuity (BCVA of < 6/12 were excluded to rule out possible pre-existing anisometropic amblyopia. Results: Of the 11 patients with significant interocular axial length difference, 5 patients were excluded on the basis of possible pre-existing amblyopia. The remaining 6 patients had final BCVA of 6/12 or better. The median length of the cataractous eyes was 2.83 mm longer than the fellow eyes (range 1.12 mm – 3.52 mm. The intraocular lens power required for emmetropia was 6.8 dioptres (range 3.5 dioptres – 11.5 dioptres less in the cataractous eyes. A refractive outcome within 1 dioptre of the target refraction was achieved in all patients. The median delay between ocular trauma and cataract surgery was 20 years (range 8–24 years. Conclusion: Significant unilateral axial length elongation may occur in adults with longstanding traumatic cataracts and visual deprivation. A potential correlation may exist between delay to surgery and degree of axial length difference. This rare phenomenon must be considered when determining intraocular lens power to avoid post-operative refractive surprises.

Abscisic Acid Stimulates Elongation of Excised Pea Root Tips

Science.gov (United States)

Gaither, Douglas H.; Lutz, Donald H.; Forrence, Leonard E.

1975-01-01

Excised Pisum sativum L. root tips were incubated in a pH 5.2 sucrose medium containing abscisic acid. Elongation growth was inhibited by 100 μm abscisic acid. However, decreasing the abscisic acid concentration caused stimulation of elongation, the maximum response (25% to 30%) occurring at 1 μm abscisic acid. Prior to two hours, stimulation of elongation by 1 μm abscisic acid was not detectable. Increased elongation did not occur in abscisic acid-treated root tips of Lens culinaris L., Phaseolus vulgaris L., or Zea mays L. PMID:16659198

Ubiquitylation and degradation of elongating RNA polymerase II

DEFF Research Database (Denmark)

Wilson, Marcus D; Harreman, Michelle; Svejstrup, Jesper Q

2013-01-01

During its journey across a gene, RNA polymerase II has to contend with a number of obstacles to its progression, including nucleosomes, DNA-binding proteins, DNA damage, and sequences that are intrinsically difficult to transcribe. Not surprisingly, a large number of elongation factors have....... In this review, we describe the mechanisms and factors responsible for the last resort mechanism of transcriptional elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation....

One-pot synthesis and electrochemical reactivity of carbon coated LiFePO4 spindles

International Nuclear Information System (INIS)

Yu Juanjuan; Hu Juncheng; Li Jinlin

2012-01-01

Highlights: ► Carbon coated LiFePO 4 spindles have been successfully synthesized via a novel supercritical method. ► The concentrations of lithium have an effect on the morphology of carbon coated LiFePO 4 . ► Amorphous carbon layer formed on the surface of LiFePO 4 by adding glucose. ► The carbon coating is responsible for the enhanced electrochemical performance. - Abstract: Spindle-like carbon coated LiFePO 4 (LiFePO 4 /C) composites have been successfully synthesized via a novel one-pot supercritical methanol method. The products were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The particle size, morphology and electrochemical reactivity changed with the concentration of lithium and carbon source. A possible morphology evolution process was also proposed. The glucose not only facilitates the formation of single crystalline LiFePO 4 , but also gives an amorphous carbon layer on the surface LiFePO 4 spindles.

Planar Elongation Measurements on Soft Elastomers

DEFF Research Database (Denmark)

Jensen, Mette Krog; Skov, Anne Ladegaard; Rasmussen, Henrik K.

2009-01-01

A new fixture to the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks. To validate this new technique, soft polymeric networks of poly(propyleneoxide) (PPO) were investigated during deformation.......A new fixture to the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks. To validate this new technique, soft polymeric networks of poly(propyleneoxide) (PPO) were investigated during deformation....

Pengaturan Kecepatan Motor Spindle pada Retrofit Mesin Bubut CNC Menggunakan Kontroler PID Gain Scheduling

Directory of Open Access Journals (Sweden)

Fikri Yoga Permana

2013-03-01

Full Text Available Pada mesin bubut Computerized Numerical Control (CNC, proses pemahatan benda kerja memerlukan kecepatan potong yang tetap agar hasil kerja memiliki tingkat presisi tinggi. Dalam prakteknya, ketika terjadi pemotongan, diameter benda kerja akan selalu berkurang dan tingkat kedalaman pahat berubah-ubah sesuai dengan proses yang dilakukan sehingga mempengaruhi kecepatan putar motor spindle sehingga mengakibatkan tingkat presisi hasil kerja menjadi berkurang. Pada penelitian ini, digunakan kontroler PI Gain Scheduling untuk mengatur kecapatan motor spindle. Hasil yang didapatkan berupa simulasi kontroler PI Gain Scheduling. Dari hasil simulasi didapatkan kontroler PI Gain Scheduling mampu membuat respon sistem sesuai dengan yang diinginkan.

"Fast" and "slow" skeleto-fusimotor innervation in cat tenuissimus spindles; a study with the glycogen-depletion method.

Science.gov (United States)

Jami, L; Lan-Couton, D; Malmgren, K; Petit, J

1978-07-01

The glycogen-depletion method was used to investigate the motor supply to tenuissimus with respect to the presence of fast beta axons and to assess the total proportion of both fast and slow beta-innervated spindles in this muscle. In a first series of 5 expts., groups of motor axons with conduction velocities higher than 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibres they innervated. The whole muscle was then quick-frozen, serially cut, stained to demonstrate glycogen and examined for intrafusal glycogen depletion. Zones of glycogen depletion were found in 16 of the 46 examined spindles; they were most frequently located in the longest of the chain intrafusal muscle fibres. Since it is known that there are no purely fusimotor axons to tenuissimus with conduction velocities above 50 m/s, it was concluded that beta axons are present among the fastest axons to this muscle. In a second series of 5 expts. as many motor axons as possible with conduction velocities above 60 m/s were stimulated. Zones of glycogen depletion were found in 19 of the 47 examined spindles. They affected chain fibres in about half of the instances and bag1 fibers in the others. As this latter location is characteristic of slow dynamic beta axons, it was concluded that both slow and fast beta axons occur regularly in the motor supply to tenuissimus. beta-innervation is present in at least 40% of tenuissimus spindles with almost no convergence of fast and slow beta axons onto the same spindle.

Halogenated auxins affect microtubules and root elongation in Lactuca sativa

Science.gov (United States)

Zhang, N.; Hasenstein, K. H.

2000-01-01

We studied the effect of 4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA), a recently described root growth stimulator, and 5,6-dichloro-indole-3-acetic acid (DCIAA) on growth and microtubule (MT) organization in roots of Lactuca sativa L. DCIAA and indole-3-butyric acid (IBA) inhibited root elongation and depolymerized MTs in the cortex of the elongation zone, inhibited the elongation of stele cells, and promoted xylem maturation. Both auxins caused the plane of cell division to shift from anticlinal to periclinal. In contrast, TFIBA (100 micromolar) promoted elongation of primary roots by 40% and stimulated the elongation of lateral roots, even in the presence of IBA, the microtubular inhibitors oryzalin and taxol, or the auxin transport inhibitor naphthylphthalamic acid. However, TFIBA inhibited the formation of lateral root primordia. Immunostaining showed that TFIBA stabilized MTs orientation perpendicular to the root axis, doubled the cortical cell length, but delayed xylem maturation. The data indicate that the auxin-induced inhibition of elongation and swelling of roots results from reoriented phragmoplasts, the destabilization of MTs in elongating cells, and promotion of vessel formation. In contrast, TFIBA induced promotion of root elongation by enhancing cell length, prolonging transverse MT orientation, delaying cell and xylem maturation.

Inhibition of muscle spindle afferent activity during masseter muscle fatigue in the rat.

Science.gov (United States)

Brunetti, Orazio; Della Torre, Giovannella; Lucchi, Maria Luisa; Chiocchetti, Roberto; Bortolami, Ruggero; Pettorossi, Vito Enrico

2003-09-01

The influence of muscle fatigue on the jaw-closing muscle spindle activity has been investigated by analyzing: (1) the field potentials evoked in the trigeminal motor nucleus (Vmot) by trigeminal mesencephalic nucleus (Vmes) stimulation, (2) the orthodromic and antidromic responses evoked in the Vmes by stimulation of the peripheral and central axons of the muscle proprioceptive afferents, and (3) the extracellular unitary discharge of masseter muscle spindles recorded in the Vmes. The masseter muscle was fatigued by prolonged tetanic masseter nerve electrical stimulation. Pre- and postsynaptic components of the potentials evoked in the Vmot showed a significant reduction in amplitude following muscle fatigue. Orthodromic and antidromic potentials recorded in the Vmes also showed a similar amplitude decrease. Furthermore, muscle fatigue caused a decrease of the discharge frequency of masseter muscle spindle afferents in most of the examined units. The inhibition of the potential amplitude and discharge frequency was strictly correlated with the extent of muscle fatigue and was mediated by the group III and IV afferent muscle fibers activated by fatigue. In fact, the inhibitory effect was abolished by capsaicin injection in the masseter muscle that provokes selective degeneration of small afferent muscle fibers containing neurokinins. We concluded that fatigue signals originating from the muscle and traveling through capsaicin-sensitive fibers are able to diminish the proprioceptive input by a central presynaptic influence. In the second part of the study, we examined the central projection of the masseter small afferents sensitive to capsaicin at the electron-microscopic level. Fiber degeneration was induced by injecting capsaicin into the masseter muscle. Degenerating terminals were found on the soma and stem process in Vmes and on the dendritic tree of neurons in Vmot. This suggests that small muscle afferents may influence the muscle spindle activity through

Muscle spindles exhibit core lesions and extensive degeneration of intrafusal fibers in the Ryr1I4895T/wt mouse model of core myopathy

International Nuclear Information System (INIS)

Zvaritch, Elena; MacLennan, David H.

2015-01-01

Muscle spindles from the hind limb muscles of adult Ryr1 I4895T/wt (IT/+) mice exhibit severe structural abnormalities. Up to 85% of the spindles are separated from skeletal muscle fascicles by a thick layer of connective tissue. Many intrafusal fibers exhibit degeneration, with Z-line streaming, compaction and collapse of myofibrillar bundles, mitochondrial clumping, nuclear shrinkage and pyknosis. The lesions resemble cores observed in the extrafusal myofibers of this animal model and of core myopathy patients. Spindle abnormalities precede those in extrafusal fibers, indicating that they are a primary pathological feature in this murine Ryr1-related core myopathy. Muscle spindle involvement, if confirmed for human core myopathy patients, would provide an explanation for an array of devastating clinical features characteristic of these diseases and provide novel insights into the pathology of RYR1-related myopathies. - Highlights: • Muscle spindles exhibit structural abnormalities in a mouse model of core myopathy. • Myofibrillar collapse and mitochondrial clumping is observed in intrafusal fibers. • Myofibrillar degeneration follows a pattern similar to core formation in extrafusal myofibers. • Muscle spindle abnormalities are a part of the pathological phenotype in the mouse model of core myopathy. • Direct involvement of muscle spindles in the pathology of human RYR1-related myopathies is proposed

Spindle Cell Carcinoma of Nasal Cavity- A Case Report

Science.gov (United States)

Mittal, Abhishek; Nagpal, Tapan

2016-01-01

Spindle Cell Carcinoma (SpCC), also known as Sarcomatoid Carcinoma, is a rare and peculiar biphasic malignant neoplasm that occurs mainly in the upper aero-digestive tract, mostly in larynx. SCC accounts for 3% of all squamous cell carcinomas (SCCs) in the head and neck region. It is a rare variant of SCC which shows spindled or pleomorphic tumour cells simulating a true sarcoma. We present a case report of SpCC nasal cavity in a 50-year-old female patient, presented with intermittent epistaxis from left nasal cavity. On physical examination, the patient had an ulcero-exophytic type of mass in the left nasal cavity and a smooth bulge on the left side of anterior hard palate. Patient underwent excision of nasal mass along with partial palatectomy by facial degloving approach and reconstruction of palate with naso-labial flap. The postoperative histopathological report showed SCC. Surgery forms the mainstay of treatment. Radiotherapy and Chemotherapy is warranted in order to improve treatment results. As only few cases have been reported, we report a case of this rare entity to contribute for better understanding and awareness of this rare malignancy. PMID:27190843

Spindle-cell squamous carcinoma of the esophagus: a tumor with biphasic morphology

International Nuclear Information System (INIS)

Agha, F.P.; Keren, D.F.

1985-01-01

Spindle-cell squamous carcinoma of the esophagus is a rare malignant tumor. It is characterized by a large bulky mass in the middle third of the esophagus with a lobulated surface and local expansion of the esophagus. This lesion may be pedunculated and cause relatively little obstruction despite its bulk. The current view, based on ultrastructure and immunohistochemical evidence, has confirmed that the sarcomatous component of the squamous cell carcinoma originates from mesenchymal metaplasia of squamous cells. On the basis of this evidence and clinical behavior, it seems appropriate to consider carcinosarcoma and pseudosarcoma as equivalents and as variants of squamous cell carcinoma. Four patients with spindle-cell squamous carcinoma, an unusual subset of squamous carcinoma, are described, and the salient radiographic and pathologic features of this disorder's distinctive biphasic morphology are discussed

Elongation of Flare Ribbons

Energy Technology Data Exchange (ETDEWEB)

Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT (United States); Cassak, Paul A. [Department of Physics and Astronomy, West Virginia University, Morgantown WV (United States); Priest, Eric R. [School of Mathematics and Statistics, University of St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)

2017-03-20

We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s{sup −1}. The shear measured from conjugate footpoints is consistent with the measurement from flare loops, and both show the decrease of shear toward a potential field as a flare evolves and ribbons and loops spread along the PIL. Flares exhibiting fast bidirectional elongation appear to have a strong shear, which may indicate a large magnetic guide field relative to the reconnection field in the coronal current sheet. We discuss how the analysis of ribbon motion could help infer properties in the corona where reconnection takes place.

Elongational viscosity of photo-oxidated LDPE

Science.gov (United States)

Rolón-Garrido, Víctor H.; Wagner, Manfred H.

2014-05-01

Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, timedeformation separability is confirmed for all samples, independent of the degree of photo-oxidation.

4-Phenylbutyrate stimulates Hsp70 expression through the Elp2 component of elongator and STAT-3 in cystic fibrosis epithelial cells.

Science.gov (United States)

Suaud, Laurence; Miller, Katelyn; Panichelli, Ashley E; Randell, Rachel L; Marando, Catherine M; Rubenstein, Ronald C

2011-12-30

Sodium 4-phenylbutyrate (4PBA) corrects trafficking of ΔF508-CFTR in Cystic Fibrosis (CF) epithelia, which is hypothesized to, at least in part, result from increased expression of Hsp70 (stress-induced 70 kDa heat shock protein). To identify other 4PBA-regulated proteins that may promote correction of ΔF508 trafficking, we performed differential display RT-PCR on mRNA from IB3-1 CF bronchiolar epithelial cells treated for 0-24 h with 1 mM 4PBA. In this screen, a STAT-3 (signal transducer and activator of transcription-3)-interacting protein, StIP-1 that regulates STAT-3 activation had transiently increased expression. StIP-1 is identical to Elongator protein 2 (Elp2), a component of the Elongator complex that regulates RNA polymerase II. Previous studies have suggested that Elongator regulates Hsp70 mRNA transcription, and that the Hsp70 promoter contains functional STAT-3-binding sites. We therefore tested the hypothesis that 4PBA increases Hsp70 expression by an Elongator- and STAT-3-dependent mechanism. 4PBA treatment of IB3-1 CF bronchiolar epithelial cells caused transiently increased expression of Hsp70 protein, as well as Elp2 protein and mRNA. Elp2 depletion by transfection of small interfering RNAs, reduced both Elp2 and Hsp70 protein expression. 4PBA also caused transient activation of STAT-3, and increased abundance of nuclear proteins that bind to the STAT-3-responsive element of the Hsp70 promoter. Luciferase reporter assays demonstrated that both Elp2 overexpression and 4PBA increase Hsp70 promoter activity, while Elp2 depletion blocked the ability of 4PBA to stimulate Hsp70 promoter activity. Together, these data suggest that Elp2 and STAT-3 mediate, at least in part, the stimulation of Hsp70 expression by 4PBA.

Bilateral elongated styloid process: Its anatomical, embryological and clinical implications

OpenAIRE

Bagoji Ishwar B, Hadimani Gavishiddappa A, Patil Balasaheb G, Bannur Balappa M,Ambadasu B

2013-01-01

The styloid process is a slender, elongated, cylindrical bony projection from temporal bone. It normally varies in length from 2 cm to 3 cm. During a routine demonstration of skull for MBBS students we found the bilateral elongated styloid process in dry human skull. The length of elongation measured on the right and left side was 6.0 & 5.9 cms respectively. Such abnormal elongation of the styloid process may cause compression on a number of vital vessels and nerves related to it, producing i...

Modeling and characterization of an electromagnetic system for the estimation of Frequency Response Function of spindle

Science.gov (United States)

Tlalolini, David; Ritou, Mathieu; Rabréau, Clément; Le Loch, Sébastien; Furet, Benoit

2018-05-01

The paper presents an electromagnetic system that has been developed to measure the quasi-static and dynamic behavior of machine-tool spindle, at different spindle speeds. This system consists in four Pulse Width Modulation amplifiers and four electromagnets to produce magnetic forces of ± 190 N for the static mode and ± 80 N for the dynamic mode up to 5 kHz. In order to measure the Frequency Response Function (FRF) of spindle, the applied force is required, which is a key issue. A dynamic force model is proposed in order to obtain the load from the measured current in the amplifiers. The model depends on the exciting frequency and on the magnetic characteristics of the system. The predicted force at high speed is validated with a specific experiment and the performance limits of the experimental device are investigated. The FRF obtained with the electromagnetic system is compared to a classical tap test measurement.

Sleep spindles: a physiological marker of age-related changes in gray matter in brain regions supporting motor skill memory consolidation.

Science.gov (United States)

Fogel, Stuart; Vien, Catherine; Karni, Avi; Benali, Habib; Carrier, Julie; Doyon, Julien

2017-01-01

Sleep is necessary for the optimal consolidation of procedural learning, and in particular, for motor sequential skills. Motor sequence learning remains intact with age, but sleep-dependent consolidation is impaired, suggesting that memory deficits for procedural skills are specifically impacted by age-related changes in sleep. Age-related changes in spindles may be responsible for impaired motor sequence learning consolidation, but the morphological basis for this deficit is unknown. Here, we found that gray matter in the hippocampus and cerebellum was positively correlated with both sleep spindles and offline improvements in performance in young participants but not in older participants. These results suggest that age-related changes in gray matter in the hippocampus relate to spindles and may underlie age-related deficits in sleep-related motor sequence memory consolidation. In this way, spindles can serve as a biological marker for structural brain changes and the related memory deficits in older adults. Copyright © 2016 Elsevier Inc. All rights reserved.

Uniaxial Elongational viscosity of bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

Using dynamic input allocation for elongation control at FTU

International Nuclear Information System (INIS)

Boncagni, L.; Galeani, S.; Granucci, G.; Varano, G.; Vitale, V.; Zaccarian, L.

2010-01-01

In this paper we exploit the dynamic allocation scheme for input redundant control systems proposed in to achieve elongation control on FTU (Frascati Tokamak Upgrade). The scheme first serves as a means for regulating the current in the F coils. Then, due to the quasi-static relationship between the plasma elongation and the F coils current, elongation control is achieved by suitably generalizing the allocation scheme. Both simulation and experimental results are reported.

LOX is a novel mitotic spindle-associated protein essential for mitosis.

Science.gov (United States)

Boufraqech, Myriem; Wei, Darmood; Weyemi, Urbain; Zhang, Lisa; Quezado, Martha; Kalab, Petr; Kebebew, Electron

2016-05-17

LOX regulates cancer progression in a variety of human malignancies. It is overexpressed in aggressive cancers and higher expression of LOX is associated with higher cancer mortality. Here, we report a new function of LOX in mitosis. We show that LOX co-localizes to mitotic spindles from metaphase to telophase, and p-H3(Ser10)-positive cells harbor strong LOX staining. Further, purification of mitotic spindles from synchronized cells show that LOX fails to bind to microtubules in the presence of nocodazole, whereas paclitaxel treated samples showed enrichment in LOX expression, suggesting that LOX binds to stabilized microtubules. LOX knockdown leads to G2/M phase arrest; reduced p-H3(Ser10), cyclin B1, CDK1, and Aurora B. Moreover, LOX knockdown significantly increased sensitivity of cancer cells to chemotherapeutic agents that target microtubules. Our findings suggest that LOX has a role in cancer cell mitosis and may be targeted to enhance the activity of microtubule inhibitors for cancer therapy.

Asymmetric Centriole Numbers at Spindle Poles Cause Chromosome Missegregation in Cancer

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Marco R. Cosenza

2017-08-01

Full Text Available Chromosomal instability is a hallmark of cancer and correlates with the presence of extra centrosomes, which originate from centriole overduplication. Overduplicated centrioles lead to the formation of centriole rosettes, which mature into supernumerary centrosomes in the subsequent cell cycle. While extra centrosomes promote chromosome missegregation by clustering into pseudo-bipolar spindles, the contribution of centriole rosettes to chromosome missegregation is unknown. We used multi-modal imaging of cells with conditional centriole overduplication to show that mitotic rosettes in bipolar spindles frequently harbor unequal centriole numbers, leading to biased chromosome capture that favors binding to the prominent pole. This results in chromosome missegregation and aneuploidy. Rosette mitoses lead to viable offspring and significantly contribute to progeny production. We further show that centrosome abnormalities in primary human malignancies frequently consist of centriole rosettes. As asymmetric centriole rosettes generate mitotic errors that can be propagated, rosette mitoses are sufficient to cause chromosome missegregation in cancer.

The Aurora B kinase in chromosome biorientation and spindle checkpoint signalling

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Veronica eKrenn

2015-10-01

Full Text Available Aurora B, a member of the Aurora family of serine/threonine protein kinases, is a key player in chromosome segregation. As part of a macromolecular complex known as the chromosome passenger complex, Aurora B concentrates early during mitosis in the proximity of centromeres and kinetochores, the sites of attachment of chromosomes to spindle microtubules. There, it contributes to a number of processes that impart fidelity to cell division, including kinetochore stabilization, kinetochore-microtubule attachment, and the regulation of a surveillance mechanism named the spindle assembly checkpoint. In the regulation of these processes, Aurora B is the fulcrum of a remarkably complex network of interactions that feed back on its localization and activation state. In this review we discuss the multiple roles of Aurora B during mitosis, focusing in particular on its role at centromeres and kinetochores. Many details of the network of interactions at these locations remain poorly understood, and we focus here on several crucial outstanding questions.

EFHC1, a protein mutated in juvenile myoclonic epilepsy, associates with the mitotic spindle through its N-terminus

International Nuclear Information System (INIS)

Nijs, Laurence de; Lakaye, Bernard; Coumans, Bernard; Leon, Christine; Ikeda, Takashi; Delgado-Escueta, Antonio V.; Grisar, Thierry; Chanas, Grazyna

2006-01-01

A novel gene, EFHC1, mutated in juvenile myoclonic epilepsy (JME) encodes a protein with three DM10 domains of unknown function and one putative EF-hand motif. To study the properties of EFHC1, we expressed EGFP-tagged protein in various cell lines. In interphase cells, the fusion protein was present in the cytoplasm and in the nucleus with specific accumulation at the centrosome. During mitosis EGFP-EFHC1 colocalized with the mitotic spindle, especially at spindle poles and with the midbody during cytokinesis. Using a specific antibody, we demonstrated the same distribution of the endogenous protein. Deletion analyses revealed that the N-terminal region of EFHC1 is crucial for the association with the mitotic spindle and the midbody. Our results suggest that EFHC1 could play an important role during cell division

Measurement and analysis of pressure tube elongation in the Douglas Point reactor

International Nuclear Information System (INIS)

Causey, A.R.; MacEwan, S.R.; Jamieson, H.C.; Mitchell, A.B.

1980-02-01

Elongations of zirconium alloy pressure tubes in CANDU reactors, which occur as a result of neutron-irradiation-induced creep and growth, have been measured over the past 6 years, and the consequences of thses elongations have recently been analysed. Elongation rates, previously deduced from extensive measurements of elongations of cold-worked Zircaloy-2 pressure tubes in the Pickering reactors, have been modified to apply to the pressure tubes in the Douglas Point (DP) reactor by taking into account measured diffences in texture and dislocation density. Using these elongation rates, and structural data unique to the DP reactor, the analysis predicts elongation behaviour which is in good agreement with pressure tube elongations measured during the ten years of reactor operation. (Auth)

Parameter Estimation of the Thermal Network Model of a Machine Tool Spindle by Self-made Bluetooth Temperature Sensor Module

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Yuan-Chieh Lo

2018-02-01

Full Text Available Thermal characteristic analysis is essential for machine tool spindles because sudden failures may occur due to unexpected thermal issue. This article presents a lumped-parameter Thermal Network Model (TNM and its parameter estimation scheme, including hardware and software, in order to characterize both the steady-state and transient thermal behavior of machine tool spindles. For the hardware, the authors develop a Bluetooth Temperature Sensor Module (BTSM which accompanying with three types of temperature-sensing probes (magnetic, screw, and probe. Its specification, through experimental test, achieves to the precision ±(0.1 + 0.0029|t| °C, resolution 0.00489 °C, power consumption 7 mW, and size Ø40 mm × 27 mm. For the software, the heat transfer characteristics of the machine tool spindle correlative to rotating speed are derived based on the theory of heat transfer and empirical formula. The predictive TNM of spindles was developed by grey-box estimation and experimental results. Even under such complicated operating conditions as various speeds and different initial conditions, the experiments validate that the present modeling methodology provides a robust and reliable tool for the temperature prediction with normalized mean square error of 99.5% agreement, and the present approach is transferable to the other spindles with a similar structure. For realizing the edge computing in smart manufacturing, a reduced-order TNM is constructed by Model Order Reduction (MOR technique and implemented into the real-time embedded system.

Multipolar spindle pole coalescence is a major source of kinetochore mis-attachment and chromosome mis-segregation in cancer cells.

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William T Silkworth

Full Text Available Many cancer cells display a CIN (Chromosome Instability phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed gamma-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells.

Stochastic model of template-directed elongation processes in biology.

Science.gov (United States)

Schilstra, Maria J; Nehaniv, Chrystopher L

2010-10-01

We present a novel modular, stochastic model for biological template-based linear chain elongation processes. In this model, elongation complexes (ECs; DNA polymerase, RNA polymerase, or ribosomes associated with nascent chains) that span a finite number of template units step along the template, one after another, with semaphore constructs preventing overtaking. The central elongation module is readily extended with modules that represent initiation and termination processes. The model was used to explore the effect of EC span on motor velocity and dispersion, and the effect of initiation activator and repressor binding kinetics on the overall elongation dynamics. The results demonstrate that (1) motors that move smoothly are able to travel at a greater velocity and closer together than motors that move more erratically, and (2) the rate at which completed chains are released is proportional to the occupancy or vacancy of activator or repressor binding sites only when initiation or activator/repressor dissociation is slow in comparison with elongation. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Spindle epithelial tumor with thymus-like differentiation of thyroid gland: Report of two cases with follow-up

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Nisa Azizun

2010-10-01

Full Text Available Spindle epithelial tumor with thymus-like differentiation (SETTLE is a rare malignant thyroid tumor showing thymic or related branchial pouch differentiation. The tumors are composed predominantly of spindle cells along with focal epithelial component and ductular formations. SETTLE occurs in young patients, with indolent growth and a tendency to develop delayed blood-borne metastases. We herein report two cases of SETTLE with a follow-up period of 64 months and 30 months, respectively.

Ketamine increases the frequency of electroencephalographic bicoherence peak on the alpha spindle area induced with propofol.

Science.gov (United States)

Hayashi, K; Tsuda, N; Sawa, T; Hagihira, S

2007-09-01

The reticular and thalamocortical system is known to play a prominent role in spindle wave activity, and the spindle wave is related to the sedative effects of anaesthetics. Recently, bispectral analysis of the EEG has been developed as a better method to indicate nonlinear regulation including the thalamocortical system linking to the cortical area. In the present study, in order to explore the interference of ketamine with the nonlinear regulation of the sub-cortical system, we examined the effect of ketamine on spindle alpha waves through the bispectral analysis. The study included 21 patients. Anaesthesia was induced and maintained using a propofol-TCI system (target-controlled infusion, with target concentration 3.5 microg ml(-1)). An A-2000 BIS monitor was used and the raw EEG signals were collected via an RS232 interface on a personal computer. Bicoherence, the normalized bispectrum, and power spectrum were analysed before and after i.v. administration of 1 mg kg(-1) racemic ketamine. Propofol caused alpha peaks in both power and bicoherence spectra, with average frequencies of 10.6 (SD 0.9) Hz and 10.7 (1.0) Hz, respectively. The addition of ketamine significantly shifted each peak to frequencies of 14.4 (1.4) Hz and 13.6 (1.5) Hz, respectively [P < 0.05, mean (SD)]. Ketamine shifted the alpha peaks of bicoherence induced by propofol to higher frequencies. This suggests that ketamine changes the alpha spindle rhythms through the modulation of the nonlinear sub-cortical reverberating network.

Phospho-Bcl-xL(Ser62) influences spindle assembly and chromosome segregation during mitosis.

Science.gov (United States)

Wang, Jianfang; Beauchemin, Myriam; Bertrand, Richard

2014-01-01

Functional analysis of a series of phosphorylation mutants reveals that Bcl-xL(Ser62Ala) influences cell entry into anaphase and mitotic exit in taxol-exposed cells compared with cells expressing wild-type Bcl-xL or a series of other phosphorylation mutants, an effect that appears to be independent of its anti-apoptotic activity. During normal mitosis progression, Bcl-xL(Ser62) is strongly phosphorylated by PLK1 and MAPK14/SAPKp38α at the prometaphase, metaphase, and the anaphase boundaries, while it is de-phosphorylated at telophase and cytokinesis. Phospho-Bcl-xL(Ser62) localizes in centrosomes with γ-tubulin and in the mitotic cytosol with some spindle-assembly checkpoint signaling components, including PLK1, BubR1, and Mad2. In taxol- and nocodazole-exposed cells, phospho-Bcl-xL(Ser62) also binds to Cdc20- Mad2-, BubR1-, and Bub3-bound complexes, while Bcl-xL(Ser62Ala) does not. Silencing Bcl-xL expression and expressing the phosphorylation mutant Bcl-xL(Ser62Ala) lead to an increased number of cells harboring mitotic spindle defects including multipolar spindle, chromosome lagging and bridging, aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h. Together, the data indicate that during mitosis, Bcl-xL(Ser62) phosphorylation impacts on spindle assembly and chromosome segregation, influencing chromosome stability. Observations of mitotic cells harboring aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h were also made with cells expressing the phosphorylation mutant Bcl-xL(Ser49Ala) and dual mutant Bcl-xL(Ser49/62Ala).

Topological defects in confined populations of spindle-shaped cells

Science.gov (United States)

Duclos, Guillaume; Erlenkämper, Christoph; Joanny, Jean-François; Silberzan, Pascal

2017-01-01

Most spindle-shaped cells (including smooth muscles and sarcomas) organize in vivo into well-aligned `nematic’ domains, creating intrinsic topological defects that may be used to probe the behaviour of these active nematic systems. Active non-cellular nematics have been shown to be dominated by activity, yielding complex chaotic flows. However, the regime in which live spindle-shaped cells operate, and the importance of cell-substrate friction in particular, remains largely unexplored. Using in vitro experiments, we show that these active cellular nematics operate in a regime in which activity is effectively damped by friction, and that the interaction between defects is controlled by the system’s elastic nematic energy. Due to the activity of the cells, these defects behave as self-propelled particles and pairwise annihilate until all displacements freeze as cell crowding increases. When confined in mesoscopic circular domains, the system evolves towards two identical +1/2 disclinations facing each other. The most likely reduced positions of these defects are independent of the size of the disk, the cells’ activity or even the cell type, but are well described by equilibrium liquid crystal theory. These cell-based systems thus operate in a regime more stable than other active nematics, which may be necessary for their biological function.

Vibration of rotating-shaft design spindles with flexible bases

Science.gov (United States)

Tseng, Chaw-Wu

The purpose of this study is to demonstrate an accurate mathematical model predicting forced vibration of rotating-shaft HDD spindle motors with flexible stationary parts. The mathematical model consists of three parts: a rotating part, a stationary part, and bearings. The rotating part includes a flexible hub, a flexible shaft press-fit into the hub, and N elastic disks mounted on the hub. The stationary part can include motor bracket (stator), base casting, and top cover. The bearings under consideration can be ball bearings or hydrodynamic bearings (HDB). The rotating disks are modelled through the classical plate theory. The rotating part (except the disks) and the stationary part are modelled through finite element analyses (FEA). With mode shapes and natural frequencies obtained from FEA, the kinetic and potential energies of the rotating and stationary parts are formulated and discretized to compensate for the gyroscopic effects from rotation. Finally, use of Lagrange equation results in the equations of motion. To verify the mathematical model, frequency response functions are measured experimentally for an HDB spindle carrying two identical disks at motor and drive levels. Experimental measurements agree very well with theoretical predictions not only in resonance frequency but also in resonance amplitude.

Nuclear starburst activity induced by elongated bulges in spiral galaxies

Science.gov (United States)

Kim, Eunbin; Kim, Sungsoo S.; Choi, Yun-Young; Lee, Gwang-Ho; de Grijs, Richard; Lee, Myung Gyoon; Hwang, Ho Seong

2018-06-01

We study the effects of bulge elongation on the star formation activity in the centres of spiral galaxies using the data from the Sloan Digital Sky Survey Data Release 7. We construct a volume-limited sample of face-on spiral galaxies with Mr nuclear starbursts using the fibre specific star formation rates derived from the SDSS spectra. We find a statistically significant correlation between bulge elongation and nuclear starbursts in the sense that the fraction of nuclear starbursts increases with bulge elongation. This correlation is more prominent for fainter and redder galaxies, which exhibit higher ratios of elongated bulges. We find no significant environmental dependence of the correlation between bulge elongation and nuclear starbursts. These results suggest that non-axisymmetric bulges can efficiently feed the gas into the centre of galaxies to trigger nuclear starburst activity.

Spindle vibration and sound field measurement using optical vibrometry

OpenAIRE

Tatar, Kourosh

2008-01-01

Mechanical systems often produce a considerable amount of vibration and noise. To be able to obtain a complete picture of the dynamic behaviour of these systems, vibration and sound measurements are of significant importance. Optical metrology is well-suited for non-intrusive measurements on complex objects. The development and the use of remote non-contact vibration measurement methods for spindles are described and vibration measurements on thin- walled structures and sound field measuremen...

Incremental elongation or ratchetting - Experimental tests and practical method of analysis (on stainless steel 304L and 306L)

International Nuclear Information System (INIS)

Cousseran, Pierre; Lebey, Jacques; Roche, Roland; Clement, Gerard; Moulin, Didier.

1980-12-01

Ratchetting, or incremental elongation can be considered as a creep enhancement when cyclic deformations are added to a primary constant load. Under examination, it appears that theoretical models proposed till now do not fit correctly the actual behavior of materials. From experimental tests results performed in Saclay, a simplified method for prevention of ratcheting is proposed. A validation was made by using experimental data from various sources [fr

FtsZ-Dependent Elongation of a Coccoid Bacterium

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Ana R. Pereira

2016-09-01

Full Text Available A mechanistic understanding of the determination and maintenance of the simplest bacterial cell shape, a sphere, remains elusive compared with that of more complex shapes. Cocci seem to lack a dedicated elongation machinery, and a spherical shape has been considered an evolutionary dead-end morphology, as a transition from a spherical to a rod-like shape has never been observed in bacteria. Here we show that a Staphylococcus aureus mutant (M5 expressing the ftsZG193D allele exhibits elongated cells. Molecular dynamics simulations and in vitro studies indicate that FtsZG193D filaments are more twisted and shorter than wild-type filaments. In vivo, M5 cell wall deposition is initiated asymmetrically, only on one side of the cell, and progresses into a helical pattern rather than into a constricting ring as in wild-type cells. This helical pattern of wall insertion leads to elongation, as in rod-shaped cells. Thus, structural flexibility of FtsZ filaments can result in an FtsZ-dependent mechanism for generating elongated cells from cocci.

MLL/WDR5 Complex Regulates Kif2A Localization to Ensure Chromosome Congression and Proper Spindle Assembly during Mitosis.

Science.gov (United States)

Ali, Aamir; Veeranki, Sailaja Naga; Chinchole, Akash; Tyagi, Shweta

2017-06-19

Mixed-lineage leukemia (MLL), along with multisubunit (WDR5, RbBP5, ASH2L, and DPY30) complex catalyzes the trimethylation of H3K4, leading to gene activation. Here, we characterize a chromatin-independent role for MLL during mitosis. MLL and WDR5 localize to the mitotic spindle apparatus, and loss of function of MLL complex by RNAi results in defects in chromosome congression and compromised spindle formation. We report interaction of MLL complex with several kinesin and dynein motors. We further show that the MLL complex associates with Kif2A, a member of the Kinesin-13 family of microtubule depolymerase, and regulates the spindle localization of Kif2A during mitosis. We have identified a conserved WDR5 interaction (Win) motif, so far unique to the MLL family, in Kif2A. The Win motif of Kif2A engages in direct interactions with WDR5 for its spindle localization. Our findings highlight a non-canonical mitotic function of MLL complex, which may have a direct impact on chromosomal stability, frequently compromised in cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

Method for Vibration Response Simulation and Sensor Placement Optimization of a Machine Tool Spindle System with a Bearing Defect

Science.gov (United States)

Cao, Hongrui; Niu, Linkai; He, Zhengjia

2012-01-01

Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response. PMID:23012514

Influence of Gradual Elongation to the Patella Tendon Insertion in Rabbits

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Hirotaka Mutsuzaki

2014-08-01

Full Text Available The purpose of this study was to examine the histological changes at the patella tendon (PT insertion site under gradual elongation in rabbits. Gradual elongation of the PT was performed using external fixation for 4 weeks, with a lengthening speed of 0.5 mm/day (elongation group; n = 24. Rabbits in the sham group underwent the same surgical procedure without gradual elongation (sham group; n = 24. Eight animals were sacrificed 1, 2 and 4 weeks after surgery in each group, respectively. Average thicknesses of stained glycosaminoglycan (GAGs areas by Safranin-O staining in the total cartilage layer and the uncalcified fibrocartilage layer in the elongation group were significantly higher than that in the sham group at 4 weeks (p < 0.05 and that in the intact PT group (n = 6, p < 0.05. In the elongation group, the peak in the average thicknesses of the stained GAGs areas in the total cartilage layer and the uncalcified fibrocartilage layer were observed at 4 weeks. Gradual elongation of PT insertion significantly affected the increase in the average thicknesses of the stained GAGs areas in the cartilage layer especially in the uncalcified fibrocartilage layer at 4 weeks in rabbits. Clinically, insertions of tendon and ligament can extend during gradual elongation using external fixation more than 4 weeks after the operation.

Tree-shoot elongation patterns in a gamma-irradiated northern forest community

International Nuclear Information System (INIS)

Buech, R.R.; Salmonson, B.J.

1977-01-01

Shoot elongation in the upper crowns of seven tree species was studied in a gamma-irradiated northern forest community near Rhinelander, Wis. Observations on the pattern and duration of shoot elongation are presented for the irradiation (1972) and postirradiation (1973) growing seasons. The gymnosperm Abies balsamea was the most radiosensitive species. Significant alteration in pattern and duration was observed in 1973 at exposure rates of 4 to 25 r/20-hr day; 31 r/20-hr day was lethal. At the other extreme, 116 r/20-hr day produced no significant effects on Acer saccharum shoot elongation pattern or duration. Acer rubrum, Betula papyrifera, Populus tremuloides, Quercus rubra, and Tilia americana were intermediate in radiosensitivity. Observed responses to radiation were alteration in the elongation pattern, suppression of internodal elongation, and death. Effects of the 1972 growing-season exposure were most obvious in the subsequent growing seasons. Retardation of initial elongation was characteristic of all species. Cessation of elongation was variable, even within species (e.g., P. tremuloides). The results suggest that bud differentiation and morphology and dependency on food reserves contributed to the lag in manifestation of radiation damage. The resultant crown characteristics are described and explained

Sleep spindle density in narcolepsy

DEFF Research Database (Denmark)

Christensen, Julie Anja Engelhard; Nikolic, Miki; Hvidtfelt, Mathias

2017-01-01

BACKGROUND: Patients with narcolepsy type 1 (NT1) show alterations in sleep stage transitions, rapid-eye-movement (REM) and non-REM sleep due to the loss of hypocretinergic signaling. However, the sleep microstructure has not yet been evaluated in these patients. We aimed to evaluate whether...... the sleep spindle (SS) density is altered in patients with NT1 compared to controls and patients with narcolepsy type 2 (NT2). METHODS: All-night polysomnographic recordings from 28 NT1 patients, 19 NT2 patients, 20 controls (C) with narcolepsy-like symptoms, but with normal cerebrospinal fluid hypocretin...... levels and multiple sleep latency tests, and 18 healthy controls (HC) were included. Unspecified, slow, and fast SS were automatically detected, and SS densities were defined as number per minute and were computed across sleep stages and sleep cycles. The between-cycle trends of SS densities in N2...

Free Vibration Analysis of a Spinning Flexible DISK-SPINDLE System Supported by Ball Bearing and Flexible Shaft Using the Finite Element Method and Substructure Synthesis

Science.gov (United States)

JANG, G. H.; LEE, S. H.; JUNG, M. S.

2002-03-01

Free vibration of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft is analyzed by using Hamilton's principle, FEM and substructure synthesis. The spinning disk is described by using the Kirchhoff plate theory and von Karman non-linear strain. The rotating spindle and stationary shaft are modelled by Rayleigh beam and Euler beam respectively. Using Hamilton's principle and including the rigid body translation and tilting motion, partial differential equations of motion of the spinning flexible disk and spindle are derived consistently to satisfy the geometric compatibility in the internal boundary between substructures. FEM is used to discretize the derived governing equations, and substructure synthesis is introduced to assemble each component of the disk-spindle-bearing-shaft system. The developed method is applied to the spindle system of a computer hard disk drive with three disks, and modal testing is performed to verify the simulation results. The simulation result agrees very well with the experimental one. This research investigates critical design parameters in an HDD spindle system, i.e., the non-linearity of a spinning disk and the flexibility and boundary condition of a stationary shaft, to predict the free vibration characteristics accurately. The proposed method may be effectively applied to predict the vibration characteristics of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft in the various forms of computer storage device, i.e., FDD, CD, HDD and DVD.

Piezoelectric self-sensing actuator for active vibration control of motorized spindle based on adaptive signal separation

Science.gov (United States)

He, Ye; Chen, Xiaoan; Liu, Zhi; Qin, Yi

2018-06-01

The motorized spindle is the core component of CNC machine tools, and the vibration of it reduces the machining precision and service life of the machine tools. Owing to the fast response, large output force, and displacement of the piezoelectric stack, it is often used as the actuator in the active vibration control of the spindle. A piezoelectric self-sensing actuator (SSA) can reduce the cost of the active vibration control system and simplify the structure by eliminating the use of a sensor, because a SSA can have both actuating and sensing functions at the same time. The signal separation method of a SSA based on a bridge circuit is widely applied because of its simple principle and easy implementation. However, it is difficult to maintain dynamic balance of the circuit. Prior research has used adaptive algorithm to balance of the bridge circuit on the flexible beam dynamically, but those algorithms need no correlation between sensing and control voltage, which limit the applications of SSA in the vibration control of the rotor-bearing system. Here, the electromechanical coupling model of the piezoelectric stack is established, followed by establishment of the dynamic model of the spindle system. Next, a new adaptive signal separation method based on the bridge circuit is proposed, which can separate relative small sensing voltage from related mixed voltage adaptively. The experimental results show that when the self-sensing signal obtained from the proposed method is used as a displacement signal, the vibration of the motorized spindle can be suppressed effectively through a linear quadratic Gaussian (LQG) algorithm.

Slow Freezing or Vitrification of Oocytes: Their Effects on Survival and Meiotic Spindles, and the Time Schedule for Clinical Practice

Directory of Open Access Journals (Sweden)

Shee-Uan Chen

2009-03-01

Full Text Available Both the slow-freezing method with increased sucrose concentration and new vitrification techniques significantly improve the results of cryopreservation of human oocytes. The recent perfection for vitrification includes the concepts of increase of cooling and warming rates using minimum volume methods, and decrease of toxicity by reducing the concentration of cryoprotectants. In the recent literature, the survival of cryopreserved oocytes ranged from 74% to 90% using the slow-freezing method and from 84% to 99% by vitrification. Overall, the survival rate of oocytes from vitrification (95%, 899/948 appeared higher than that of the slow-freezing method (75%, 1,275/1,683. The microtubules of meiotic spindles are vulnerable to the thermal changes and will depolymerize. After incubation, the microtubules repolymerize. Spindle recovery is faster after vitrification than slow freezing. Even so, after 3 hours of incubation, spindle recuperation is similar between vitrification and slow freezing. Considering both aspects of spindle recovery and oocyte aging, the time schedule for oocyte cryopreservation program makes fertilization in the optimal time. Intracytoplasmic sperm injection is performed for oocytes at 3 hours of post-thaw incubation from the slow-freezing method and 2 hours from vitrification, with restoration of meiotic spindles. The pregnancy potential of cryopreserved oocytes is comparable to that of fresh oocytes or frozen embryos. Cryopreservation of oocytes would importantly contribute to oocyte donation and preservation of fertility for cancer patients.

Relations between ultrastructure of mitotic spindle and chromosome translocation

OpenAIRE

Jadwiga A. Tarkowska

2014-01-01

Dividing endosperm cells of Haemanthus katherinae Bak. treated with an 0.25 per cent mixture of water-soluble glycosides from Nerium oleander were insepected in a light microscope (LM) and severe disturbances were found in all phases of mitosis. The same cells were observed in the electron microscope (EM) and relations were noted and analysed between the chromosome arrangement and the submicroscopic structure of the mitotuc spindle. The successive steps in the disintegration of the formed spi...

Plane of vertebral movement eliciting muscle lengthening history in the low back influences the decrease in muscle spindle responsiveness of the cat.

Science.gov (United States)

Ge, Weiqing; Cao, Dong-Yuan; Long, Cynthia R; Pickar, Joel G

2011-12-01

Proprioceptive feedback is thought to play a significant role in controlling both lumbopelvic and intervertebral orientations. In the lumbar spine, a vertebra's positional history along the dorsal-ventral axis has been shown to alter the position, movement, and velocity sensitivity of muscle spindles in the multifidus and longissimus muscles. These effects appear due to muscle history. Because spinal motion segments have up to 6 degrees of freedom for movement, we were interested in whether the axis along which the history is applied differentially affects paraspinal muscle spindles. We tested the null hypothesis that the loading axis, which creates a vertebra's positional history, has no effect on a lumbar muscle spindle's subsequent response to vertebral position or movement. Identical displacements were applied along three orthogonal axes directly at the L(6) spinous process using a feedback motor system under displacement control. Single-unit nerve activity was recorded from 60 muscle spindle afferents in teased filaments from L(6) dorsal rootlets innervating intact longissimus or multifidus muscles of deeply anesthetized cats. Muscle lengthening histories along the caudal-cranial and dorsal-ventral axis, compared with the left-right axis, produced significantly greater reductions in spindle responses to vertebral position and movement. The spinal anatomy suggested that the effect of a lengthening history is greatest when that history had occurred along an axis lying within the anatomical plane of the facet joint. Speculation is made that the interaction between normal spinal mechanics and the inherent thixotropic property of muscle spindles poses a challenge for feedback and feedforward motor control of the lumbar spine.

Mutual interdependence of splicing and transcription elongation.

Science.gov (United States)

Brzyżek, Grzegorz; Świeżewski, Szymon

2015-01-01

Transcription and splicing are intrinsically linked, as splicing needs a pre-mRNA substrate to commence. The more nuanced view is that the rate of transcription contributes to splicing regulation. On the other hand there is accumulating evidence that splicing has an active role in controlling transcription elongation by DNA-dependent RNA polymerase II (RNAP II). We briefly review those mechanisms and propose a unifying model where splicing controls transcription elongation to provide an optimal timing for successive rounds of splicing.

Finite Element Analysis of Flexural Vibrations in Hard Disk Drive Spindle Systems

Science.gov (United States)

LIM, SEUNGCHUL

2000-06-01

This paper is concerned with the flexural vibration analysis of the hard disk drive (HDD) spindle system by means of the finite element method. In contrast to previous research, every system component is here analytically modelled taking into account its structural flexibility and also the centrifugal effect particularly on the disk. To prove the effectiveness and accuracy of the formulated models, commercial HDD systems with two and three identical disks are selected as examples. Then their major natural modes are computed with only a small number of element meshes as the shaft rotational speed is varied, and subsequently compared with the existing numerical results obtained using other methods and newly acquired experimental ones. Based on such a series of studies, the proposed method can be concluded as a very promising tool for the design of HDDs and various other high-performance computer disk drives such as floppy disk drives, CD ROM drives, and their variations having spindle mechanisms similar to those of HDDs.

p600 regulates spindle orientation in apical neural progenitors and contributes to neurogenesis in the developing neocortex

Directory of Open Access Journals (Sweden)

Camille Belzil

2014-05-01

Full Text Available Apical neural progenitors (aNPs drive neurogenesis by means of a program consisting of self-proliferative and neurogenic divisions. The balance between these two manners of division sustains the pool of apical progenitors into late neurogenesis, thereby ensuring their availability to populate the brain with terminal cell types. Using knockout and in utero electroporation mouse models, we report a key role for the microtubule-associated protein 600 (p600 in the regulation of spindle orientation in aNPs, a cellular event that has been associated with cell fate and neurogenesis. We find that p600 interacts directly with the neurogenic protein Ndel1 and that aNPs knockout for p600, depleted of p600 by shRNA or expressing a Ndel1-binding p600 fragment all display randomized spindle orientation. Depletion of p600 by shRNA or expression of the Ndel1-binding p600 fragment also results in a decreased number of Pax6-positive aNPs and an increased number of Tbr2-positive basal progenitors destined to become neurons. These Pax6-positive aNPs display a tilted mitotic spindle. In mice wherein p600 is ablated in progenitors, the production of neurons is significantly impaired and this defect is associated with microcephaly. We propose a working model in which p600 controls spindle orientation in aNPs and discuss its implication for neurogenesis.

A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia

Energy Technology Data Exchange (ETDEWEB)

Burland, T.G.; Paul, E.C.A.; Oetliker, M.; Dove, W.F.

1988-03-01

The multinucleate plasmodium of Physarum polycephalum is unusual among eucaryotic cells in that it uses tubulins only in mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent in this cell type. The authors identified a ..beta..-tubulin cDNA clone, ..beta..105, which is shown to correspond to the transcript of the betC ..beta..-tubulin locus and to encode ..beta..2 tubulin, the ..beta.. tubulin expressed specifically in the plasmodium and used exclusively in the mitotic spindle. Physarum amoebae utilize tubulins in the cytoskeleton, centrioles, and flagella, in addition to the mitotic spindle. Sequence analysis shows that ..beta..2 tubulin is only 83% identical to the two ..beta.. tubulins expressed in amoebae. This compares with 70 to 83% identity between Physarum ..beta..2 tubulin and the ..beta.. tubulins of yeasts, fungi, alga, trypanosome, fruit fly, chicken, and mouse. On the other hand, Physarum ..beta..2 tubulin is no more similar to, for example, Aspergillus ..beta.. tubulins than it is to those of Drosophila melanogaster or mammals. Several eucaryotes express at least one widely diverged ..beta.. tubulin as well as one or more ..beta.. tubulins that conform more closely to a consensus ..beta..-tubulin sequence. The authors suggest that ..beta..-tubulins diverge more when their expression pattern is restricted, especially when this restriction results in their use in fewer functions. This divergence among ..beta.. tubulins could have resulted through neutral drift. For example, exclusive use of Physarum ..beta..2 tubulin in the spindle may have allowed more amino acid substitutions than would be functionally tolerable in the ..beta.. tubulins that are utilized in multiple microtubular organelles. Alternatively, restricted use of ..beta.. tubulins may allow positive selection to operate more freely to refine ..beta..-tubulin function.

Evolution and Allometry of Calcaneal Elongation in Living and Extinct Primates

Science.gov (United States)

Boyer, Doug M.; Seiffert, Erik R.; Gladman, Justin T.; Bloch, Jonathan I.

2013-01-01

Specialized acrobatic leaping has been recognized as a key adaptive trait tied to the origin and subsequent radiation of euprimates based on its observed frequency in extant primates and inferred frequency in extinct early euprimates. Hypothesized skeletal correlates include elongated tarsal elements, which would be expected to aid leaping by allowing for increased rates and durations of propulsive acceleration at takeoff. Alternatively, authors of a recent study argued that pronounced distal calcaneal elongation of euprimates (compared to other mammalian taxa) was related primarily to specialized pedal grasping. Testing for correlations between calcaneal elongation and leaping versus grasping is complicated by body size differences and associated allometric affects. We re-assess allometric constraints on, and the functional significance of, calcaneal elongation using phylogenetic comparative methods, and present an evolutionary hypothesis for the evolution of calcaneal elongation in primates using a Bayesian approach to ancestral state reconstruction (ASR). Results show that among all primates, logged ratios of distal calcaneal length to total calcaneal length are inversely correlated with logged body mass proxies derived from the area of the calcaneal facet for the cuboid. Results from phylogenetic ANOVA on residuals from this allometric line suggest that deviations are explained by degree of leaping specialization in prosimians, but not anthropoids. Results from ASR suggest that non-allometric increases in calcaneal elongation began in the primate stem lineage and continued independently in haplorhines and strepsirrhines. Anthropoid and lorisid lineages show stasis and decreasing elongation, respectively. Initial increases in calcaneal elongation in primate evolution may be related to either development of hallucal-grasping or a combination of grasping and more specialized leaping behaviors. As has been previously suggested, subsequent increases in calcaneal

FUSIMOTOR EFFECTS OF MIDBRAIN STIMULATION ON JAW MUSCLE-SPINDLES OF THE ANESTHETIZED CAT

NARCIS (Netherlands)

TAYLOR, A; JUCH, PJW

The effects of electrical stimulation within the midbrain on fusimotor output to the jaw elevator muscles were studied in anaesthetized cats. Muscle spindle afferents recorded in the mesencephalic trigeminal nucleus were categorised as primary or secondary by their responses to succinylcholine

QTL analysis of internode elongation in response to gibberellin in deepwater rice

OpenAIRE

Nagai, Keisuke; Kondo, Yuma; Kitaoka, Takuya; Noda, Tomonori; Kuroha, Takeshi; Angeles-Shim, Rosalyn B.; Yasui, Hideshi; Yoshimura, Atsushi; Ashikari, Motoyuki

2014-01-01

Gibberellin (GA) is a plant hormone that has important roles in numerous plant developmental phases. Rice plants known as deepwater rice respond to flooding by elongating their internodes to avoid anoxia. Previous studies reported that GA is essential for internode elongation in deepwater rice. Quantitative trait locus (QTL) analyses identified QTLs regulating internode elongation in response to deepwater conditions. However, the interaction between internode elongation and regulators of GA s...

Gibberellin biosynthesis and signal transduction is essential for internode elongation in deepwater rice.

Science.gov (United States)

Ayano, Madoka; Kani, Takahiro; Kojima, Mikiko; Sakakibara, Hitoshi; Kitaoka, Takuya; Kuroha, Takeshi; Angeles-Shim, Rosalyn B; Kitano, Hidemi; Nagai, Keisuke; Ashikari, Motoyuki

2014-10-01

Under flooded conditions, the leaves and internodes of deepwater rice can elongate above the water surface to capture oxygen and prevent drowning. Our previous studies showed that three major quantitative trait loci (QTL) regulate deepwater-dependent internode elongation in deepwater rice. In this study, we investigated the age-dependent internode elongation in deepwater rice. We also investigated the relationship between deepwater-dependent internode elongation and the phytohormone gibberellin (GA) by physiological and genetic approach using a QTL pyramiding line (NIL-1 + 3 + 12). Deepwater rice did not show internode elongation before the sixth leaf stage under deepwater condition. Additionally, deepwater-dependent internode elongation occurred on the sixth and seventh internodes during the sixth leaf stage. These results indicate that deepwater rice could not start internode elongation until the sixth leaf stage. Ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) method for the phytohormone contents showed a deepwater-dependent GA1 and GA4 accumulation in deepwater rice. Additionally, a GA inhibitor abolished deepwater-dependent internode elongation in deepwater rice. On the contrary, GA feeding mimicked internode elongation under ordinary growth conditions. However, mutations in GA biosynthesis and signal transduction genes blocked deepwater-dependent internode elongation. These data suggested that GA biosynthesis and signal transduction are essential for deepwater-dependent internode elongation in deepwater rice. © 2014 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

Investigation the gas film in micro scale induced error on the performance of the aerostatic spindle in ultra-precision machining

Science.gov (United States)

Chen, Dongju; Huo, Chen; Cui, Xianxian; Pan, Ri; Fan, Jinwei; An, Chenhui

2018-05-01

The objective of this work is to study the influence of error induced by gas film in micro-scale on the static and dynamic behavior of a shaft supported by the aerostatic bearings. The static and dynamic balance models of the aerostatic bearing are presented by the calculated stiffness and damping in micro scale. The static simulation shows that the deformation of aerostatic spindle system in micro scale is decreased. For the dynamic behavior, both the stiffness and damping in axial and radial directions are increased in micro scale. The experiments of the stiffness and rotation error of the spindle show that the deflection of the shaft resulting from the calculating parameters in the micro scale is very close to the deviation of the spindle system. The frequency information in transient analysis is similar to the actual test, and they are also higher than the results from the traditional case without considering micro factor. Therefore, it can be concluded that the value considering micro factor is closer to the actual work case of the aerostatic spindle system. These can provide theoretical basis for the design and machining process of machine tools.

Proprioceptive Feedback through a Neuromorphic Muscle Spindle Model

Directory of Open Access Journals (Sweden)

Lorenzo Vannucci

2017-06-01

Full Text Available Connecting biologically inspired neural simulations to physical or simulated embodiments can be useful both in robotics, for the development of a new kind of bio-inspired controllers, and in neuroscience, to test detailed brain models in complete action-perception loops. The aim of this work is to develop a fully spike-based, biologically inspired mechanism for the translation of proprioceptive feedback. The translation is achieved by implementing a computational model of neural activity of type Ia and type II afferent fibers of muscle spindles, the primary source of proprioceptive information, which, in mammals is regulated through fusimotor activation and provides necessary adjustments during voluntary muscle contractions. As such, both static and dynamic γ-motoneurons activities are taken into account in the proposed model. Information from the actual proprioceptive sensors (i.e., motor encoders is then used to simulate the spindle contraction and relaxation, and therefore drive the neural activity. To assess the feasibility of this approach, the model is implemented on the NEST spiking neural network simulator and on the SpiNNaker neuromorphic hardware platform and tested on simulated and physical robotic platforms. The results demonstrate that the model can be used in both simulated and real-time robotic applications to translate encoder values into a biologically plausible neural activity. Thus, this model provides a completely spike-based building block, suitable for neuromorphic platforms, that will enable the development of sensory-motor closed loops which could include neural simulations of areas of the central nervous system or of low-level reflexes.

Treated wastewater phytotoxicity assessment using Lactuca sativa: Focus on germination and root elongation test parameters.

Science.gov (United States)

Priac, Anne; Badot, Pierre-Marie; Crini, Grégorio

2017-03-01

Sensitive and simple ecotoxicological bioassays like seed germination and root elongation tests are commonly used to evaluate the phytotoxicity of waste and industrial discharge waters. Although the tests are performed following national and international standards, various parameters such as the number of seeds per dish, the test duration or the type of support used remain variable. To be able to make a correct comparison of results from different studies, it is crucial to know which parameter(s) could affect ecotoxicological diagnosis. We tested four different control waters and three seed densities. No significant differences on either germination rate or root elongation endpoints were shown. Nevertheless, we found that the four lettuce cultivars (Appia, batavia dorée de printemps, grosse blonde paresseuse, and Kinemontepas) showed significantly different responses when watered with the same and different metal-loaded industrial discharge water. From the comparison, it is clear that a differential sensitivity scale occurs among not just species but cultivars. Copyright © 2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Sleep spindle-related reactivation of category-specific cortical regions after learning face-scene associations

DEFF Research Database (Denmark)

Bergmann, Til O; Mölle, Matthias; Diedrichs, Jens

2012-01-01

Newly acquired declarative memory traces are believed to be reactivated during NonREM sleep to promote their hippocampo-neocortical transfer for long-term storage. Yet it remains a major challenge to unravel the underlying neuronal mechanisms. Using simultaneous electroencephalography (EEG......-coupled reactivation of brain regions representing the specific task stimuli was traced during subsequent NonREM sleep with EEG-informed fMRI. Relative to the control task, learning face-scene associations triggered a stronger combined activation of neocortical and hippocampal regions during subsequent sleep. Notably......) and functional magnetic resonance imaging (fMRI) recordings in humans, we show that sleep spindles play a key role in the reactivation of memory-related neocortical representations. On separate days, participants either learned face-scene associations or performed a visuomotor control task. Spindle...

A Role for the Chaperone Complex BAG3-HSPB8 in Actin Dynamics, Spindle Orientation and Proper Chromosome Segregation during Mitosis.

Science.gov (United States)

Fuchs, Margit; Luthold, Carole; Guilbert, Solenn M; Varlet, Alice Anaïs; Lambert, Herman; Jetté, Alexandra; Elowe, Sabine; Landry, Jacques; Lavoie, Josée N

2015-10-01

The co-chaperone BAG3, in complex with the heat shock protein HSPB8, plays a role in protein quality control during mechanical strain. It is part of a multichaperone complex that senses damaged cytoskeletal proteins and orchestrates their seclusion and/or degradation by selective autophagy. Here we describe a novel role for the BAG3-HSPB8 complex in mitosis, a process involving profound changes in cell tension homeostasis. BAG3 is hyperphosphorylated at mitotic entry and localizes to centrosomal regions. BAG3 regulates, in an HSPB8-dependent manner, the timely congression of chromosomes to the metaphase plate by influencing the three-dimensional positioning of the mitotic spindle. Depletion of BAG3 caused defects in cell rounding at metaphase and dramatic blebbing of the cortex associated with abnormal spindle rotations. Similar defects were observed upon silencing of the autophagic receptor p62/SQSTM1 that contributes to BAG3-mediated selective autophagy pathway. Mitotic cells depleted of BAG3, HSPB8 or p62/SQSTM1 exhibited disorganized actin-rich retraction fibres, which are proposed to guide spindle orientation. Proper spindle positioning was rescued in BAG3-depleted cells upon addition of the lectin concanavalin A, which restores cortex rigidity. Together, our findings suggest the existence of a so-far unrecognized quality control mechanism involving BAG3, HSPB8 and p62/SQSTM1 for accurate remodelling of actin-based mitotic structures that guide spindle orientation.

A Role for the Chaperone Complex BAG3-HSPB8 in Actin Dynamics, Spindle Orientation and Proper Chromosome Segregation during Mitosis.

Directory of Open Access Journals (Sweden)

Margit Fuchs

2015-10-01

Full Text Available The co-chaperone BAG3, in complex with the heat shock protein HSPB8, plays a role in protein quality control during mechanical strain. It is part of a multichaperone complex that senses damaged cytoskeletal proteins and orchestrates their seclusion and/or degradation by selective autophagy. Here we describe a novel role for the BAG3-HSPB8 complex in mitosis, a process involving profound changes in cell tension homeostasis. BAG3 is hyperphosphorylated at mitotic entry and localizes to centrosomal regions. BAG3 regulates, in an HSPB8-dependent manner, the timely congression of chromosomes to the metaphase plate by influencing the three-dimensional positioning of the mitotic spindle. Depletion of BAG3 caused defects in cell rounding at metaphase and dramatic blebbing of the cortex associated with abnormal spindle rotations. Similar defects were observed upon silencing of the autophagic receptor p62/SQSTM1 that contributes to BAG3-mediated selective autophagy pathway. Mitotic cells depleted of BAG3, HSPB8 or p62/SQSTM1 exhibited disorganized actin-rich retraction fibres, which are proposed to guide spindle orientation. Proper spindle positioning was rescued in BAG3-depleted cells upon addition of the lectin concanavalin A, which restores cortex rigidity. Together, our findings suggest the existence of a so-far unrecognized quality control mechanism involving BAG3, HSPB8 and p62/SQSTM1 for accurate remodelling of actin-based mitotic structures that guide spindle orientation.

Serial elongation derotation flexion (EDF) casting for patients with infantile and juvenile scoliosis.

Science.gov (United States)

Canavese, Federico; Rousset, Marie; Mansour, Mounira; Samba, Antoine; Dimeglio, Alain

2016-02-01

Infantile and juvenile scoliosis, among different types of spinal deformity, is still a challenge for pediatric orthopedic surgeons. The ideal treatment of infantile and juvenile scoliosis has not yet been identified as both clinicians and surgeons still face multiple challenges, including preservation of the thoracic spine, thoracic cage, lung growth and cardiac function without reducing spinal motion. Elongation, derotation, flexion (EDF) casting technique is a custom-made thoracolumbar cast based on a three dimensional correction concept. This cast offers three-dimensional correction and can control the evolution of the deformity in some cases. Spinal growth can be guided by EDF casting as it can influence the initially curved spine to grow straighter. This article aimed to provide a comprehensive review of how infantile and juvenile scoliosis can affect normal spine and thorax and how these deformities can be treated with serial EDF casting technique. A current literature review is mandatory in order to understand the principles of the serial EDF casting technique and the effectiveness of conservative treatment in young and very young patients.

Transition zone cells reach G2 phase before initiating elongation in maize root apex

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M. Victoria Alarcón

2017-06-01

Full Text Available Root elongation requires cell divisions in the meristematic zone and cell elongation in the elongation zone. The boundary between dividing and elongating cells is called the transition zone. In the meristem zone, initial cells are continuously dividing, but on the basal side of the meristem cells exit the meristem through the transition zone and enter in the elongation zone, where they stop division and rapidly elongate. Throughout this journey cells are accompanied by changes in cell cycle progression. Flow cytometry analysis showed that meristematic cells are in cycle, but exit when they enter the elongation zone. In addition, the percentage of cells in G2 phase (4C strongly increased from the meristem to the elongation zone. However, we did not observe remarkable changes in the percentage of cells in cell cycle phases along the entire elongation zone. These results suggest that meristematic cells in maize root apex stop the cell cycle in G2 phase after leaving the meristem.

Adenylate cyclase regulates elongation of mammalian primary cilia

International Nuclear Information System (INIS)

Ou, Young; Ruan, Yibing; Cheng, Min; Moser, Joanna J.; Rattner, Jerome B.; Hoorn, Frans A. van der

2009-01-01

The primary cilium is a non-motile microtubule-based structure that shares many similarities with the structures of flagella and motile cilia. It is well known that the length of flagella is under stringent control, but it is not known whether this is true for primary cilia. In this study, we found that the length of primary cilia in fibroblast-like synoviocytes, either in log phase culture or in quiescent state, was confined within a range. However, when lithium was added to the culture to a final concentration of 100 mM, primary cilia of synoviocytes grew beyond this range, elongating to a length that was on average approximately 3 times the length of untreated cilia. Lithium is a drug approved for treating bipolar disorder. We dissected the molecular targets of this drug, and observed that inhibition of adenylate cyclase III (ACIII) by specific inhibitors mimicked the effects of lithium on primary cilium elongation. Inhibition of GSK-3β by four different inhibitors did not induce primary cilia elongation. ACIII was found in primary cilia of a variety of cell types, and lithium treatment of these cell types led to their cilium elongation. Further, we demonstrate that different cell types displayed distinct sensitivities to the lithium treatment. However, in all cases examined primary cilia elongated as a result of lithium treatment. In particular, two neuronal cell types, rat PC-12 adrenal medulla cells and human astrocytes, developed long primary cilia when lithium was used at or close to the therapeutic relevant concentration (1-2 mM). These results suggest that the length of primary cilia is controlled, at least in part, by the ACIII-cAMP signaling pathway.

Adenylate cyclase regulates elongation of mammalian primary cilia

Energy Technology Data Exchange (ETDEWEB)

Ou, Young; Ruan, Yibing; Cheng, Min; Moser, Joanna J. [Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada); Rattner, Jerome B. [Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada); Hoorn, Frans A. van der, E-mail: fvdhoorn@ucalgary.ca [Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada)

2009-10-01

The primary cilium is a non-motile microtubule-based structure that shares many similarities with the structures of flagella and motile cilia. It is well known that the length of flagella is under stringent control, but it is not known whether this is true for primary cilia. In this study, we found that the length of primary cilia in fibroblast-like synoviocytes, either in log phase culture or in quiescent state, was confined within a range. However, when lithium was added to the culture to a final concentration of 100 mM, primary cilia of synoviocytes grew beyond this range, elongating to a length that was on average approximately 3 times the length of untreated cilia. Lithium is a drug approved for treating bipolar disorder. We dissected the molecular targets of this drug, and observed that inhibition of adenylate cyclase III (ACIII) by specific inhibitors mimicked the effects of lithium on primary cilium elongation. Inhibition of GSK-3{beta} by four different inhibitors did not induce primary cilia elongation. ACIII was found in primary cilia of a variety of cell types, and lithium treatment of these cell types led to their cilium elongation. Further, we demonstrate that different cell types displayed distinct sensitivities to the lithium treatment. However, in all cases examined primary cilia elongated as a result of lithium treatment. In particular, two neuronal cell types, rat PC-12 adrenal medulla cells and human astrocytes, developed long primary cilia when lithium was used at or close to the therapeutic relevant concentration (1-2 mM). These results suggest that the length of primary cilia is controlled, at least in part, by the ACIII-cAMP signaling pathway.

Intimal spindle cell sarcoma masquerading as adult-onset symptomatic pulmonic stenosis: a case report and review of the literature.

Science.gov (United States)

Manmadhan, Arun; Malhotra, Sunil P; Weinberg, Catherine R; Reyentovich, Alex; Latson, Larry A; Bhatla, Puneet; Saric, Muhamed

2017-10-30

Pulmonary artery intimal spindle cell sarcomas are rare and carry with them a poor prognosis and high rate of recurrence. In extremely rare cases, this tumor can infiltrate the pulmonic valve and manifest as adult-onset pulmonic stenosis. We report an unusual case of a patient with symptomatic, adult-onset severe pulmonic stenosis who was referred for possible balloon valvuloplasty but was subsequently found to have pulmonary artery intimal sarcoma infiltrating the pulmonary valve leading to progressive exertional dyspnea. The presence of adult-onset pulmonic stenosis should prompt the clinician to investigate further as most cases of pulmonic stenosis are congenital in nature and present early in life. Careful diagnostic evaluation in concert with multimodal imaging should take place to arrive at the correct and challenging diagnosis of sarcoma-induced adult-onset severe pulmonic stenosis. Given the poor prognosis and rapid progression of disease, early diagnosis is crucial.

Mucinous tubular and spindle cell carcinoma of kidney: A rare case report and review of the literature

Directory of Open Access Journals (Sweden)

Geramizadeh Bita

2009-10-01

Full Text Available Low grade mucinous tubular and spindle cell carcinoma of kidney was newly established as a distinct renal cell carcinoma in the World Health Organization (WHO classification of 2004. Until now, less than 60 cases have been reported and the largest series represented approximately 15 patients with this type of tumor. Herein, we report a case of mucinous tubular and spindle cell carcinoma in a 63-year-old male presented with right flank pain which was diagnosed after nephrectomy. Pathologists should consider this diagnosis and its spectrum of histopathologic features in mind to ensure an accurate diagnosis.

Critical Importance of Protein 4.1 in Centrosome and Mitiotic Spindle Aberrations in Breast Cancer Pathogenesis

National Research Council Canada - National Science Library

Krauss, Sharon W

2005-01-01

Important pathological hallmarks of many breast cancers include centrosome amplification, spindle pole defects leading to aberrant chromosome segregation, altered nucleoskeletal proteins and perturbed cytokinesis...

Film dosimetry of small elongated electron beams for treatment planning

International Nuclear Information System (INIS)

Niroomand-Rad, A.

1989-01-01

The characteristics of 5, 7, 10, 12, 15, and 18 Mev electron beams for small elongated fields of dimensions L x W (where L=1, 2, 3, 4, 5, and 10 cm; and W=1, 2, 3, 4, 5, and 10 cm) have been studied. Film dosimetry and parallel-plate ion chamber measurements have been used to obtain various dose parameters. Selective results of a series of systematic measurements for central axis depth dose data, uniformity index, field flatness, and relative output factors of small elongated electron beams are reported. The square-root method is employed to predict the beam data of small elongated electron fields from corresponding small square electron fields using film dosimetry. The single parameter area/perimeter radio A/P is used to characterize the relative output factors of elongated electron beams. It is our conclusion that for clinical treatment planning square-root method may be applied with caution in determining the beam characteristics of small elongated electron fields from film dosimetry. The calculated and estimated relative output factors from square-root method and A/P ratio are in good agreement and show agreement to within 1% with the measured film values

Spindle cell oncocytoma of adenohypophysis: Cytogenetics and β-catenin findings with pathology differential diagnosis and review of the literature

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Jianwu Xie

2017-09-01

Full Text Available Spindle cell oncocytoma (SCO is an extremely rare neoplasm arising in the anterior pituitary. We report comprehensive pathological description of a case of SCO in a 60 year-old male who presented with nausea, vomiting and severe hyponatremia, and pan hypopituitarism. Magnetic resonance imaging (MRI showed a 3.1 × 2.3 × 2.0 cm homogeneously enhancing bilobed mass within the sella turcica and suprasellar cistern. Intraoperative frozen section and touch imprint cytology showed cohesive spindle cells with abundant oncocytic cytoplasm. Histologic sections revealed the tumor was composed of interlacing fascicles of compact spindled cells with abundant dense oncocytic cytoplasm. There was no mitosis or necrosis present. Ki-67 index varied in areas, with an average of 3%. By immunohistochemistry (IHC, the tumor cells were negative for Cam5.2, AE1/3, neurofilament (NF, NeuN, glial fibrillary acidic protein (GFAP and synaptophysin, and strongly positive for vimentin, TTF-1 and EMA. S-100 showed focal weakly positivity. By electron microscopy (EM, the cytoplasm of the spindle cells contained numerous abundant, back-to-back, uniform, round, normal-sized mitochondria with long and lamellar cristae. Beta-catenin showed diffuse membranous and partial cytoplasmic positivity. Cytogenetic analysis showed extra copies of chromosome 1 (74%, up to 8 copies, and loss of chromosome 2 (35%. The histogenesis, classification and differential diagnosis are discussed.

Mammalian neurogenesis requires Treacle-Plk1 for precise control of spindle orientation, mitotic progression, and maintenance of neural progenitor cells.

Directory of Open Access Journals (Sweden)

Daisuke Sakai

Full Text Available The cerebral cortex is a specialized region of the brain that processes cognitive, motor, somatosensory, auditory, and visual functions. Its characteristic architecture and size is dependent upon the number of neurons generated during embryogenesis and has been postulated to be governed by symmetric versus asymmetric cell divisions, which mediate the balance between progenitor cell maintenance and neuron differentiation, respectively. The mechanistic importance of spindle orientation remains controversial, hence there is considerable interest in understanding how neural progenitor cell mitosis is controlled during neurogenesis. We discovered that Treacle, which is encoded by the Tcof1 gene, is a novel centrosome- and kinetochore-associated protein that is critical for spindle fidelity and mitotic progression. Tcof1/Treacle loss-of-function disrupts spindle orientation and cell cycle progression, which perturbs the maintenance, proliferation, and localization of neural progenitors during cortical neurogenesis. Consistent with this, Tcof1(+/- mice exhibit reduced brain size as a consequence of defects in neural progenitor maintenance. We determined that Treacle elicits its effect via a direct interaction with Polo-like kinase1 (Plk1, and furthermore we discovered novel in vivo roles for Plk1 in governing mitotic progression and spindle orientation in the developing mammalian cortex. Increased asymmetric cell division, however, did not promote increased neuronal differentiation. Collectively our research has therefore identified Treacle and Plk1 as novel in vivo regulators of spindle fidelity, mitotic progression, and proliferation in the maintenance and localization of neural progenitor cells. Together, Treacle and Plk1 are critically required for proper cortical neurogenesis, which has important implications in the regulation of mammalian brain size and the pathogenesis of congenital neurodevelopmental disorders such as microcephaly.

Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis

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Borek, Weronika E.; Groocock, Lynda M.; Samejima, Itaru; Zou, Juan; de Lima Alves, Flavia; Rappsilber, Juri; Sawin, Kenneth E.

2015-01-01

Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. PMID:26243668

The Spindle Assembly Checkpoint in Arabidopsis Is Rapidly Shut Off during Severe Stress.

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Komaki, Shinichiro; Schnittger, Arp

2017-10-23

The spindle assembly checkpoint (SAC) in animals and yeast assures equal segregation of chromosomes during cell division. The prevalent occurrence of polyploidy in flowering plants together with the observation that many plants can be readily forced to double their genomes by application of microtubule drugs raises the question of whether plants have a proper SAC. Here, we provide a functional framework of the core SAC proteins in Arabidopsis. We reveal that Arabidopsis will delay mitosis in a SAC-dependent manner if the spindle is perturbed. However, we also show that the molecular architecture of the SAC is unique in plants. Moreover, the SAC is short-lived and cannot stay active for more than 2 hr, after which the cell cycle is reset. This resetting opens the possibility for genome duplications and raises the hypothesis that a rapid termination of a SAC-induced mitotic arrest provides an adaptive advantage for plants impacting plant genome evolution. Copyright © 2017 Elsevier Inc. All rights reserved.

Spindle cell carcinoma of the breast as complex cystic lesion: a case report

International Nuclear Information System (INIS)

Kitada, Masahiro; Hayashi, Satoshi; Matsuda, Yoshinari; Ishibashi, Kei; Oikawa, Keisuke; Miyokawa, Naoyuki

2014-01-01

Spindle cell carcinoma of the breast is a rare tumor. This tumor can proliferate rapidly and cause cystic changes because of internal tissue necrosis. We evaluated a 54-year-old woman with right breast lump. Mammography showed a category four mass with a diameter of 2.5 cm. Ultrasonography (US) revealed a complex cystic lesion, and fine-needle aspiration (FNA) cytology demonstrated bloody fluid and malignant cells. Partial breast resection and sentinel lymph node biopsy were performed. Immunohistology revealed spindle cells with positive results for cytokeratin (AE1/AE3) and vimentin, partially positive results for s-100, and negative results for desmin and α-actin. The pathological stage was IIA, and biochemical characterization showed that the tumor was triple negative. Six courses of FEC-100 chemotherapy (5-fluorouracil 500 mg/m 2 , epirubicin 100 mg/m 2 , and cyclophosphamide 500 mg/m 2 ) were administered. Radiotherapy was performed. This case is discussed with reference to the literature

Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

Science.gov (United States)

Prabhu, S.; Pudukudy, M.; Sohila, S.; Harish, S.; Navaneethan, M.; Navaneethan, D.; Ramesh, R.; Hayakawa, Y.

2018-05-01

In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

Uni-axial Elongational Viscosity of Linear and Branched polymer melts

DEFF Research Database (Denmark)

Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

2005-01-01

About 40 years ago interest in the measurement of elongational viscosity of polymer melts started to grow. Here we present measurements of transient (and steady) uni-axial elongational viscosity, using the FSR, of the following melts: Four narrow MMD polystyrene (PS) samples with weight......-average molar mass Mw in the range of 50k to 390k. Three different bi-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements.The measurements on the bi-disperse PS...... melts have demonstrated that both the transient and steady elongational viscosity is quite sensitive to polydispersity. Bi-disperse PS resembles the behaviour of mono-disperse melts only at elongational rates larger then the inverse of maximal time constant of the smallest molecule. As observed in Boger...

Light quality and elongation growth. 1: Effect of duration and time of far red irradiation on stem elongation of Argyranthemum frutescens cv. Silver Leaf

International Nuclear Information System (INIS)

Jatzkowski, M.; Zimmer, K.

1994-01-01

The phenomenon of stem elongation by far red irradiation was shown with Argyranthemum frutescens 'Silver Leaf'. Stem elongation was promoted by incandescent lighting (mainly far red) during the day and night period. More intense reactions were observed with the isolated application during the nighttime. Reaction was strongly modified by the point of time the application took place. No effect could be shown by lighting with incandescent lamps for two hours during the daytime given within the first six hours of the main light period. During the nighttime two hours of lighting (incandescent lamps) promoted stem elongation atany point of time, especially in the middle of the dark period

The SUMO protease SENP1 is required for cohesion maintenance and mitotic arrest following spindle poison treatment

Energy Technology Data Exchange (ETDEWEB)

Era, Saho [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Abe, Takuya; Arakawa, Hiroshi [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Kobayashi, Shunsuke [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Szakal, Barnabas [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Yoshikawa, Yusuke; Motegi, Akira; Takeda, Shunichi [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Branzei, Dana, E-mail: dana.branzei@ifom.eu [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy)

2012-09-28

Highlights: Black-Right-Pointing-Pointer SENP1 knockout chicken DT40 cells are hypersensitive to spindle poisons. Black-Right-Pointing-Pointer Spindle poison treatment of SENP1{sup -/-} cells leads to increased mitotic slippage. Black-Right-Pointing-Pointer Mitotic slippage in SENP1{sup -/-} cells associates with apoptosis and endoreplication. Black-Right-Pointing-Pointer SENP1 counteracts sister chromatid separation during mitotic arrest. Black-Right-Pointing-Pointer Plk1-mediated cohesion down-regulation is involved in colcemid cytotoxicity. -- Abstract: SUMO conjugation is a reversible posttranslational modification that regulates protein function. SENP1 is one of the six SUMO-specific proteases present in vertebrate cells and its altered expression is observed in several carcinomas. To characterize SENP1 role in genome integrity, we generated Senp1 knockout chicken DT40 cells. SENP1{sup -/-} cells show normal proliferation, but are sensitive to spindle poisons. This hypersensitivity correlates with increased sister chromatid separation, mitotic slippage, and apoptosis. To test whether the cohesion defect had a causal relationship with the observed mitotic events, we restored the cohesive status of sister chromatids by introducing the TOP2{alpha}{sup +/-} mutation, which leads to increased catenation, or by inhibiting Plk1 and Aurora B kinases that promote cohesin release from chromosomes during prolonged mitotic arrest. Although TOP2{alpha} is SUMOylated during mitosis, the TOP2{alpha}{sup +/-} mutation had no obvious effect. By contrast, inhibition of Plk1 or Aurora B rescued the hypersensitivity of SENP1{sup -/-} cells to colcemid. In conclusion, we identify SENP1 as a novel factor required for mitotic arrest and cohesion maintenance during prolonged mitotic arrest induced by spindle poisons.

Synthesis of spindle-shaped AgI/TiO{sub 2} nanoparticles with enhanced photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Yang, Liu; Gao, Minggang; Dai, Bin; Guo, Xuhong; Liu, Zhiyong; Peng, Banghua, E-mail: banghuapeng@hotmail.com

2016-11-15

Highlights: • Nanoporous spindle-shaped AgI/TiO{sub 2} was synthesized by the solvothermal approach. • The spindle-shaped TiO{sub 2} was an excellent support for loading nanoparticles, such as AgI, transferring electrons quickly from AgI, which is beneficial for stabilizing the AgI. • AgI/TiO{sub 2} nanoparticles showed enhanced absorption intensity in the visible region and exhibited excellent photocatalytic activity. - Abstract: A novel synthetic route has been developed to prepare silver iodide (AgI) loaded spindle-shaped TiO{sub 2} nanoparticles (NPs). The morphology and crystallinity characterization revealed that small AgI NPs, with an average diameter of 15 nm were dispersed on the surface and interior of nanoporous anatase TiO{sub 2} support. High-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) surface area, Raman and X-ray photoelectron spectroscopy (XPS) were used to identify the nanoporous structure of TiO{sub 2} and the existence of AgI NPs. Diffuse reflectance spectra (DRS) showed that AgI/TiO{sub 2} composite exhibited a remarkable enhancement of visible light absorption, which is ascribed to the addition of AgI. For illustrating the superior property of this hybrid as photocatalyst, the degradation experiments were carried out for processing rhodamine B (RhB) solution under visible light irradiation and it was found that the photocatalytic activity was dramatically improved for AgI/TiO{sub 2} compared with nanoporous TiO{sub 2} and commercial P25 TiO{sub 2}. The enhanced photocatalytic properties could be attributed to the large surface area of porous TiO{sub 2}, good stability of AgI particles, and the effective charge separation due to the synergetic effect between AgI and TiO{sub 2} that can facilitate the separation of electron-hole pairs. Our novel composite based on nanoporous spindle-shaped TiO{sub 2} represents a promising new pathway for the design of high-performance photocatalysts for environmental

The nucleoporin MEL-28 promotes RanGTP-dependent γ-tubulin recruitment and microtubule nucleation in mitotic spindle formation.

Science.gov (United States)

Yokoyama, Hideki; Koch, Birgit; Walczak, Rudolf; Ciray-Duygu, Fulya; González-Sánchez, Juan Carlos; Devos, Damien P; Mattaj, Iain W; Gruss, Oliver J

2014-01-01

The GTP-bound form of the Ran GTPase (RanGTP), produced around chromosomes, drives nuclear envelope and nuclear pore complex (NPC) re-assembly after mitosis. The nucleoporin MEL-28/ELYS binds chromatin in a RanGTP-regulated manner and acts to seed NPC assembly. Here we show that, upon mitotic NPC disassembly, MEL-28 dissociates from chromatin and re-localizes to spindle microtubules and kinetochores. MEL-28 directly binds microtubules in a RanGTP-regulated way via its C-terminal chromatin-binding domain. Using Xenopus egg extracts, we demonstrate that MEL-28 is essential for RanGTP-dependent microtubule nucleation and spindle assembly, independent of its function in NPC assembly. Specifically, MEL-28 interacts with the γ-tubulin ring complex and recruits it to microtubule nucleation sites. Our data identify MEL-28 as a RanGTP target that functions throughout the cell cycle. Its cell cycle-dependent binding to chromatin or microtubules discriminates MEL-28 functions in interphase and mitosis, and ensures that spindle assembly occurs only after NPC breakdown.

Scattering phaseshift formulas for mesons and baryons in elongated boxes

Science.gov (United States)

Lee, Frank X.; Alexandru, Andrei

2018-03-01

We derive Lüscher phaseshift formulas for two-particle states in boxes elongated in one of the dimensions. Such boxes offer a cost-effective way of varying the relative momentum of the particles. Boosted states in the elongated direction, which allow wider access to energies, are also considered. The formulas for the various scenarios (moving and zero-momentum states in cubic and elongated boxes) are compared and relations between them are clarified. The results are applicable to a wide set of meson-meson and meson-baryon elastic scattering processes, with the two-particle system having equal or unequal masses.

Discontinuation of orthokeratology on eyeball elongation (DOEE).

Science.gov (United States)

Cho, P; Cheung, S W

2017-04-01

To evaluate and compare changes in axial elongation, over a 14-month period, in subjects who discontinued and then resumed ortho-k lens wear with those who continued to wear their lenses or spectacles following a 2-year myopia control study. This single masked, prospective study recruited subjects who had just completed a 2-year myopia control study. Ortho-k subjects were classified as Group OKc, in which subjects continued ortho-k lens wear for the duration of the study; or Group OKd in which subjects discontinued lens wear for seven months and wore single-vision spectacles (Phase I) and then resumed ortho-k lens wear for another seven months (Phase II). Spectacle-wearing control subjects from the initial myopia control study continued wearing spectacles as control subjects. Axial lengths were measured at scheduled visits using the IOLMaster. Thirteen, 16, and 15 Control, OKc, and OKd subjects, aged 8-14 years, respectively completed the study. Significant increase in axial elongation was found in OKd subjects only in Phase I but not in Phase II. On resuming lens wear, in Phase II, the rate of axial elongation was no longer significantly different from those of the Control or OKc subjects. Stopping ortho-k lens wear at or before the age of 14 years led to a more rapid increase in axial length; comparable to those wearing spectacles during the initial 2-year myopia control study, but greater than the Control and OKc group in this study. Axial elongation slowed again with resumed lens wear after six months. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Viscosity overshoot in the start-up of uniaxial elongation of low density polyethylene melts

DEFF Research Database (Denmark)

Rasmussen, Henrik K.; Nielsen, Jens Kromann; Bach, Anders

2005-01-01

The transient uniaxial elongational viscosity of BASF Lupolen 1840D and 3020D melts has been measured on a filament stretch rheometer up to Hencky strains of 6-7. The elongational viscosity of both melts was measured at 130 degrees C within a broad range of elongational rates. At high elongation ...

Effect of dispersion hardening process on elongation of EN AB-43200 silumin

Directory of Open Access Journals (Sweden)

J. Pezda

2008-12-01

Full Text Available Aluminum alloys belong to the second, after ferrous alloys, group of material having the biggest application in technology. Mass of metal structures is of important value, what involves lightweight mass of materials used in a given structure. Lightweight metals are used more and more often in metal structures, whereas aluminum and its alloys are the most widespread. Mechanical and technological properties of castings produced from Al-Si alloys depend on correct melting and pouring process, design of the castings and moulds and their heat treatments. Reduction of production costs requires selection of optimal parameters of the heat treatment (temperatures and durations of the treatments.The paper describes implementation of the ATD method to determination of hyperquenching and ageing treatments of EN AB-43200 (AK9 silumin. Investigated alloy was melted in electric resistance furnace. In the next stage the alloy underwent the treatment of refining and modification. Course of crystallization is presented with use of thermal-derivative analysis (ATD. That method was also used to determination of temperature range of heat treatments of the alloy. Obtained results apply to solidification curves recorded with use of the ATD method, light microscopy, strength tests and determination of an effect of heat treatment parameters on A5 elongation of the investigated alloy. On base of the performed tests of heat treated alloys there was determined an effect of selected parameters on obtained elongation (A5.

Machinability evaluation of titanium alloys (Part 2)--Analyses of cutting force and spindle motor current.

Science.gov (United States)

Kikuchi, Masafumi; Okuno, Osamu

2004-12-01

To establish a method of determining the machinability of dental materials for CAD/CAM systems, the machinability of titanium, two titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb), and free-cutting brass was evaluated through cutting force and spindle motor current. The metals were slotted using a milling machine and square end mills at four cutting conditions. Both the static and dynamic components of the cutting force represented well the machinability of the metals tested: the machinability of Ti-6Al-4V and Ti-6Al-7Nb was worse than that of titanium, while that of free-cutting brass was better. On the other hand, the results indicated that the spindle motor current was not sensitive enough to detect the material difference among the titanium and its alloys.

Photo-oxidation of LDPE: Effects on elongational viscosity

Science.gov (United States)

Rolón-Garrido, Víctor H.; Wagner, Manfred H.

2013-04-01

Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, time-deformation separability is confirmed for all samples, independent of the degree of photo-oxidation.

Bilateral elongated styloid process: Its anatomical, embryological and clinical implications

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Bagoji Ishwar B, Hadimani Gavishiddappa A, Patil Balasaheb G, Bannur Balappa M,Ambadasu B

2013-04-01

Full Text Available The styloid process is a slender, elongated, cylindrical bony projection from temporal bone. It normally varies in length from 2 cm to 3 cm. During a routine demonstration of skull for MBBS students we found the bilateral elongated styloid process in dry human skull. The length of elongation measured on the right and left side was 6.0 & 5.9 cms respectively. Such abnormal elongation of the styloid process may cause compression on a number of vital vessels and nerves related to it, producing inflammatory changes that include continuous chronic pain in the pharyngeal region. Mechanical stresses stretching the second brachial arch during fetal development probably induce variable involvement of Reichert’s cartilage in morphogenesis of the styloid process. It is important that clinicians especially dentists and otolaryngologists are aware of the natural variations of the styloid process and do not consider the styloid process with a length of 30 mm as an abnormality or as an anomaly.

An Equatorial Contractile Mechanism Drives Cell Elongation but not Cell Division

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Denker, Elsa; Bhattachan, Punit; Deng, Wei; Mathiesen, Birthe T.; Jiang, Di

2014-01-01

Cell shape changes and proliferation are two fundamental strategies for morphogenesis in animal development. During embryogenesis of the simple chordate Ciona intestinalis, elongation of individual notochord cells constitutes a crucial stage of notochord growth, which contributes to the establishment of the larval body plan. The mechanism of cell elongation is elusive. Here we show that although notochord cells do not divide, they use a cytokinesis-like actomyosin mechanism to drive cell elongation. The actomyosin network forming at the equator of each notochord cell includes phosphorylated myosin regulatory light chain, α-actinin, cofilin, tropomyosin, and talin. We demonstrate that cofilin and α-actinin are two crucial components for cell elongation. Cortical flow contributes to the assembly of the actomyosin ring. Similar to cytokinetic cells, membrane blebs that cause local contractions form at the basal cortex next to the equator and participate in force generation. We present a model in which the cooperation of equatorial actomyosin ring-based constriction and bleb-associated contractions at the basal cortex promotes cell elongation. Our results demonstrate that a cytokinesis-like contractile mechanism is co-opted in a completely different developmental scenario to achieve cell shape change instead of cell division. We discuss the occurrences of actomyosin rings aside from cell division, suggesting that circumferential contraction is an evolutionally conserved mechanism to drive cell or tissue elongation. PMID:24503569

Intimal spindle cell sarcoma masquerading as adult-onset symptomatic pulmonic stenosis: a case report and review of the literature

Directory of Open Access Journals (Sweden)

Arun Manmadhan

2017-10-01

Full Text Available Abstract Background Pulmonary artery intimal spindle cell sarcomas are rare and carry with them a poor prognosis and high rate of recurrence. In extremely rare cases, this tumor can infiltrate the pulmonic valve and manifest as adult-onset pulmonic stenosis. Case presentation We report an unusual case of a patient with symptomatic, adult-onset severe pulmonic stenosis who was referred for possible balloon valvuloplasty but was subsequently found to have pulmonary artery intimal sarcoma infiltrating the pulmonary valve leading to progressive exertional dyspnea. Conclusion The presence of adult-onset pulmonic stenosis should prompt the clinician to investigate further as most cases of pulmonic stenosis are congenital in nature and present early in life. Careful diagnostic evaluation in concert with multimodal imaging should take place to arrive at the correct and challenging diagnosis of sarcoma-induced adult-onset severe pulmonic stenosis. Given the poor prognosis and rapid progression of disease, early diagnosis is crucial.

Bir1 Deletion Causes Malfunction of the Spindle Assembly Checkpoint and Apoptosis in Yeast

International Nuclear Information System (INIS)

Ren, Qun; Liou, Liang-Chun; Gao, Qiuqiang; Bao, Xiaoming; Zhang, Zhaojie

2012-01-01

Cell division in yeast is a highly regulated and well studied event. Various checkpoints are placed throughout the cell cycle to ensure faithful segregation of sister chromatids. Unexpected events, such as DNA damage or oxidative stress, cause the activation of checkpoint(s) and cell cycle arrest. Malfunction of the checkpoints may induce cell death. We previously showed that under oxidative stress, the budding yeast cohesin Mcd1, a homolog of human Rad21, was cleaved by the caspase-like protease Esp1. The cleaved Mcd1 C-terminal fragment was then translocated to mitochondria, causing apoptotic cell death. In the present study, we demonstrated that Bir1 plays an important role in spindle assembly checkpoint and cell death. Similar to H 2 O 2 treatment, deletion of BIR1 using a BIR1-degron strain caused degradation of the securin Pds1, which binds and inactivates Esp1 until metaphase-anaphase transition in a normal cell cycle. BIR1 deletion caused an increase level of ROS and mis-location of Bub1, a major protein for spindle assembly checkpoint. In wild type, Bub1 was located at the kinetochores, but was primarily in the cytoplasm in bir1 deletion strain. When BIR1 was deleted, addition of nocodazole was unable to retain the Bub1 localization on kinetochores, further suggesting that Bir1 is required to activate and maintain the spindle assembly checkpoint. Our study suggests that the BIR1 function in cell cycle regulation works in concert with its anti-apoptosis function.

Depletion of a Drosophila homolog of yeast Sup35p disrupts spindle assembly, chromosome segregation, and cytokinesis during male meiosis.

Science.gov (United States)

Basu, J; Williams, B C; Li, Z; Williams, E V; Goldberg, M L

1998-01-01

In the course of a genetic screen for male-sterile mutations in Drosophila affecting chromosome segregation during the meiotic divisions in spermatocytes, we identified the mutation dsup35(63D). Examination of mutant testes showed that chromosome misbehavior was a consequence of major disruptions in meiotic spindle assembly. These perturbations included problems in aster formation, separation, and migration around the nuclear envelope; aberrations in spindle organization and integrity; and disappearance of the ana/telophase central spindle, which in turn disrupts cytokinesis. The dsup35(63D) mutation is caused by a P element insertion that affects, specifically in the testis, the expression of a gene (dsup35) encoding the Drosophila homolog of the yeast Sup35p and Xenopus eRF3 proteins. These proteins are involved in the termination of polypeptide synthesis on ribosomes, but previous studies have suggested that Sup35p and closely related proteins of the same family also interact directly with microtubules. An affinity-purified antibody directed against the product of the dsup35 gene was prepared; interestingly, this antibody specifically labels primary spermatocytes in one or two discrete foci of unknown structure within the nucleoplasm. We discuss how depletion of the dsup35 gene product in spermatocytes might lead to the global disruptions in meiotic spindle assembly seen in mutant spermatocytes.

Dgp71WD is required for the assembly of the acentrosomal Meiosis I spindle, and is not a general targeting factor for the γ-TuRC

Directory of Open Access Journals (Sweden)

Richard F. Reschen

2012-03-01

Dgp71WD/Nedd1 proteins are essential for mitotic spindle formation. In human cells, Nedd1 targets γ-tubulin to both centrosomes and spindles, but in other organisms the function of Dgp71WD/Nedd1 is less clear. In Drosophila cells, Dgp71WD plays a major part in targeting γ-tubulin to spindles, but not centrosomes, while in Xenopus egg extracts, Nedd1 acts as a more general microtubule (MT organiser that can function independently of γ-tubulin. The interpretation of these studies, however, is complicated by the fact that some residual Dgp71WD/Nedd1 is likely present in the cells/extracts analysed. Here we generate a Dgp71WD null mutant lacking all but the last 12 nucleotides of coding sequence. The complete loss of Dgp71WD has no quantifiable effect on γ-tubulin or Centrosomin recruitment to the centrosome in larval brain cells. The recruitment of γ-tubulin to spindle MTs, however, is severely impaired, and spindle MT density is reduced in a manner that is indistinguishable from cells lacking Augmin or γ-TuRC function. In contrast, the absence of Dgp71WD leads to defects in the assembly of the acentrosomal female Meiosis I spindle that are more severe than those seen in Augmin or γ-TuRC mutants, indicating that Dgp71WD has additional functions that are independent of these complexes in oocytes. Moreover, the localisation of bicoid RNA during oogenesis, which requires γ-TuRC function, is unperturbed in Dgp71WD120 mutants. Thus, Dgp71WD is not simply a general cofactor required for γ-TuRC and/or Augmin targeting, and it appears to have a crucial role independent of these complexes in the acentrosomal Meiosis I spindle.

Controllable synthesis of spindle-like ZnO nanostructures by a simple low-temperature aqueous solution route

International Nuclear Information System (INIS)

Lu Hongxia; Zhao Yunlong; Yu Xiujun; Chen Deliang; Zhang Liwei; Xu Hongliang; Yang Daoyuan; Wang Hailong; Zhang Rui

2011-01-01

Spindle-like ZnO nanostructures were successfully synthesized through direct precipitation of zinc acetate aqueous solution at 60 deg. C. Phase structure, morphology and microstructure of the products were investigated by X-ray diffraction, TG-DTA, FTIR and field emission scanning electron microscopy (FESEM). Result showed that hexagonal wurtzite structure ZnO nanostructures with about 100 nm in diameter and 100-200 nm in length were obtained. HMTA acted as a soft template in the process and played an important role in the formation of spindle-like ZnO nanostructures. Meanwhile, different morphologies were also obtained by altering synthetic temperature, additional agents and the ratios of Zn 2+ /OH - . Possible mechanism for the variations of morphology with synthesis parameters was also discussed in this paper.

Thermal Error Test and Intelligent Modeling Research on the Spindle of High Speed CNC Machine Tools

Science.gov (United States)

Luo, Zhonghui; Peng, Bin; Xiao, Qijun; Bai, Lu

2018-03-01

Thermal error is the main factor affecting the accuracy of precision machining. Through experiments, this paper studies the thermal error test and intelligent modeling for the spindle of vertical high speed CNC machine tools in respect of current research focuses on thermal error of machine tool. Several testing devices for thermal error are designed, of which 7 temperature sensors are used to measure the temperature of machine tool spindle system and 2 displacement sensors are used to detect the thermal error displacement. A thermal error compensation model, which has a good ability in inversion prediction, is established by applying the principal component analysis technology, optimizing the temperature measuring points, extracting the characteristic values closely associated with the thermal error displacement, and using the artificial neural network technology.

Spindle orientation bias in gut epithelial stem cell compartments is lost in precancerous tissue

NARCIS (Netherlands)

Quyn, A.J.; Appleton, P.L.; Carey, F.A.; Steele, R.J.; Barker, N.; Clevers, H.; Ridgway, R.A.; Sansom, O.J.; Nathke, I.S.

2010-01-01

The importance of asymmetric divisions for stem cell function and maintenance is well established in the developing nervous system and the skin; however, its role in gut epithelium and its importance for tumorigenesis is still debated. We demonstrate alignment of mitotic spindles perpendicular to

Critical Importance of Protein 4.1 in Centrosome and Mitotic Spindle Aberrations in Breast Cancer Pathogenesis

National Research Council Canada - National Science Library

Krauss, Sharon W

2006-01-01

We proposed to test the novel hypothesis that protein 4.1 is of critical importance to centrosome and mitotic spindle aberrations that directly impact aspects of breast cancer pathogenesis. We characterized...

Localization of spindle checkpoint proteins in cells undergoing mitosis with unreplicated genomes.

Science.gov (United States)

Johnson, Mary Kathrine; Cooksey, Amanda M; Wise, Dwayne A

2008-11-01

CHO cells can be arrested with hydoxyurea at the beginning of the DNA synthesis phase of the cell cycle. Subsequent treatment with the xanthine, caffeine, induces cells to bypass the S-phase checkpoint and enter unscheduled mitosis [Schlegel and Pardee,1986, Science 232:1264-1266]. These treated cells build a normal spindle and distribute kinetochores, unattached to chromosomes, to their daughter cells [Brinkley et al.,1988, Nature 336:251-254; Zinkowski et al.,1991, J Cell Biol 113:1091-1110; Wise and Brinkley,1997, Cell Motil Cytoskeleton 36:291-302; Balczon et al.,2003, Chromosoma 112:96-102]. To investigate how these cells distribute kinetochores to daughter cells, we analyzed the spindle checkpoint components, Mad2, CENP-E, and the 3F3 phosphoepitope, using immunofluorescence and digital microscopy. Even though the kinetochores were unpaired and DNA was fragmented, the tension, alignment, and motor components of the checkpoint were found to be present and localized as predicted in prometaphase and metaphase. This unusual mitosis proves that a cell can successfully localize checkpoint proteins and divide even when kinetochores are unpaired and fragmented. (c) 2008 Wiley-Liss, Inc.

Triangular relationship between sleep spindle activity, general cognitive ability and the efficiency of declarative learning.

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Caroline Lustenberger

Full Text Available EEG sleep spindle activity (SpA during non-rapid eye movement (NREM sleep has been reported to be associated with measures of intelligence and overnight performance improvements. The reticular nucleus of the thalamus is generating sleep spindles in interaction with thalamocortical connections. The same system enables efficient encoding and processing during wakefulness. Thus, we examined if the triangular relationship between SpA, measures of intelligence and declarative learning reflect the efficiency of the thalamocortical system. As expected, SpA was associated with general cognitive ability, e.g. information processing speed. SpA was also associated with learning efficiency, however, not with overnight performance improvement in a declarative memory task. SpA might therefore reflect the efficiency of the thalamocortical network and can be seen as a marker for learning during encoding in wakefulness, i.e. learning efficiency.

Changes in microtubule overlap length regulate kinesin-14-driven microtubule sliding

Czech Academy of Sciences Publication Activity Database

Braun, Marcus; Lánský, Zdeněk; Szuba, A.; Schwarz, F. W.; Mitra, A.; Gao, M.; Luedecke, A.; ten Wolde, P.R.; Diez, S.

2017-01-01

Roč. 13, č. 12 (2017), s. 1245-1252 ISSN 1552-4450 R&D Projects: GA ČR(CZ) GA15-17488S; GA ČR(CZ) GA17-12496Y; GA ČR(CZ) GJ17-12496Y; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:86652036 Keywords : SPINDLE ELONGATION * MITOTIC SPINDLE * KINESIN-5 CIN8 * CROSS-LINKERS Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biophysics Impact factor: 15.066, year: 2016

Adherens junction distribution mechanisms during cell-cell contact elongation in Drosophila.

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Gabrielle Goldenberg

Full Text Available During Drosophila gastrulation, amnioserosa (AS cells flatten and spread as an epithelial sheet. We used AS morphogenesis as a model to investigate how adherens junctions (AJs distribute along elongating cell-cell contacts in vivo. As the contacts elongated, total AJ protein levels increased along their length. However, genetically blocking this AJ addition indicated that it was not essential for maintaining AJ continuity. Implicating other remodeling mechanisms, AJ photobleaching revealed non-directional lateral mobility of AJs along the elongating contacts, as well as local AJ removal from the membranes. Actin stabilization with jasplakinolide reduced AJ redistribution, and live imaging of myosin II along elongating contacts revealed fragmented, expanding and contracting actomyosin networks, suggesting a mechanism for lateral AJ mobility. Actin stabilization also increased total AJ levels, suggesting an inhibition of AJ removal. Implicating AJ removal by endocytosis, clathrin endocytic machinery accumulated at AJs. However, dynamin disruption had no apparent effect on AJs, suggesting the involvement of redundant or dynamin-independent mechanisms. Overall, we propose that new synthesis, lateral diffusion, and endocytosis play overlapping roles to populate elongating cell-cell contacts with evenly distributed AJs in this in vivo system.

(R)-β-lysine-modified elongation factor P functions in translation elongation

DEFF Research Database (Denmark)

Bullwinkle, Tammy J; Zou, S Betty; Rajkovic, Andrei

2013-01-01

Post-translational modification of bacterial elongation factor P (EF-P) with (R)-β-lysine at a conserved lysine residue activates the protein in vivo and increases puromycin reactivity of the ribosome in vitro. The additional hydroxylation of EF-P at the same lysine residue by the YfcM protein has......-(β)-lysyl-EF-P showed 30% increased puromycin reactivity but no differences in dipeptide synthesis rates when compared with the β-lysylated form. Unlike disruption of the other genes required for EF-P modification, deletion of yfcM had no phenotypic consequences in Salmonella. Taken together, our findings indicate...

Methanol as an alternative electron donor in chain elongation for butyrate and caproate formation

OpenAIRE

Chen, W.S.; Ye, Y.; Steinbusch, K.J.J.; Strik, D.P.B.T.B.; Buisman, C.J.N.

2016-01-01

Chain elongation is an emerging mixed culture biotechnology converting acetate into valuable biochemicals by using ethanol as an external electron donor. In this study we proposed to test another potential electron donor, methanol, in chain elongation. Methanol can be produced through the thermochemical conversion of lignocellulosic biowaste. Use of methanol in chain elongation integrates the lignocellulosic feedstocks and the thermochemical platform technologies into chain elongation. After ...

A comparative study of using spindle motor power and eddy current for the detection of tool conditions in milling processes

OpenAIRE

Abbass, JK; Al-Habaibeh, A

2015-01-01

This paper investigates the use of the power of the driving motor of a CNC spindle in comparison to two perpendicular eddy current sensors for the detection of tool wear in milling processes. Monitoring the power through the current profile is a low cost system which has been utilised in this study as an attempt to detect the fluctuation in the motor load as a result of the conditions of the cutting tool. Eddy current sensors are dedicated sensors that are installed on the spindle to measure ...

Rhizome elongation and seagrass clonal growth

NARCIS (Netherlands)

Marbà, N.; Duarte, C.M.

1998-01-01

A compilation of published and original data on rhizome morphometry, horizontal and vertical elongation rates and branching patterns for 27 seagrass species developing in 192 seagrass stands allowed an examination of the variability of seagrass rhizome and clonal growth programmes across and within

Separation and estimation of muscle spindle and tension receptor populations by vibration of the biceps muscle in the frog.

Science.gov (United States)

Giszter, S F; Kargo, W J

2002-10-01

Frog spinal cord reflex behaviors have been used to test the idea of spinal primitives. We have suggested a significant role for proprioception in regulation of primitives. However the in vivo behavior of spindle and golgi tendon receptors in frogs in response to vibration are not well described and the proportions of these proprioceptors are not established. In this study, we examine the selectivity of muscle vibration in the spinal frog. The aim of the study was (1) to examine how hindlimb muscle spindles and GTO receptors are activated by muscle vibration and (2) to estimate the relative numbers of GTO receptors and spindle afferents in a selected muscle, for comparison with the mammal. Single muscle afferents from the biceps muscle were identified in the dorsal roots. These were tested in response to biceps vibration, intramuscular stimulation and biceps nerve stimulation. Biceps units were categorized into two types: First, spindle afferents which had a high conduction velocity (approximately 20-30 m/s), responded reliably (were entrained 1:1) to muscle vibration, and exhibited distinct pauses to shortening muscle contractions. Second, golgi tendon organ afferents, which had a lower conduction velocity (approximately 10-20 m/s), responded less reliably to muscle vibration at physiologic muscle lengths, but responded more reliably at extended lengths or with background muscle contraction, and exhibited distinct bursts to shortening muscle contractions. Vibration responses of these units were tested with and without muscle curarization. Ensemble (suction electrode) recordings from the dorsal roots were used to provide rough estimates of the proportions of the two muscle afferent types.

Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia

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Wen Jun Jiang

2017-03-01

Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.

Impaired rate of microsomal fatty acid elongation in undernourished neonatal rat brain

International Nuclear Information System (INIS)

Yeh, Y.Y.

1986-01-01

Hypomyelination caused by undernourishment in characterized by low concentrations of myelin lipids and marked reduction in lignocerate (C/sub 24:0/) and nervonate (C/sub 24:1/) moiety of cerebroside and sulfatide. Since microsomal elongation is the major source of long chain (22 to 24 carbons) fatty acids in the brain, the effect of neonatal undernourishment on acyl elongation was investigated. Undernourishment of suckling rats were induced after birth by restricting maternal dietary intake to 40% of that consumed by dams fed ad libitum. Neonates suckled by the normally fed dams served as controls. Microsomal elongation was measured as nmol from [2- 14 C] malonyl CoA incorporated/h per mg of protein. At 19 days of age, rates of behenoyl CoA (C/sub 22:0/) and erucoyl CoA (C/sub 22:1/) elongation in whole brain of undernourished neonates were 30-40% lower than that of the control, whereas the elongation rates of acyl CoA 16, 18 and 20 carbons in length either saturated or monounsaturated were similar in both groups. Undernourishment had no effect on cytoplasmic de novo fatty acid synthesis from acetyl CoA. If there are multiple elongation factors, the results indicate that the depressed activity of elongating enzyme(s) for C/sub 22:0/ and C/sub 22:1/ is an important contributing factor in lowering S/sub 24:0/ and C/sub 24:1/ content in cerebroside and sulfatide. This impairment may be a specific lesion leading to hypomyelination in undernourished rats

Improved lithium-ion battery anode capacity with a network of easily fabricated spindle-like carbon nanofibers.

Science.gov (United States)

Liu, Mengting; Xie, Wenhe; Gu, Lili; Qin, Tianfeng; Hou, Xiaoyi; He, Deyan

2016-01-01

A novel network of spindle-like carbon nanofibers was fabricated via a simplified synthesis involving electrospinning followed by preoxidation in air and postcarbonization in Ar. Not only was the as-obtained carbon network comprised of beads of spindle-like nanofibers but the cubic MnO phase and N elements were successfully anchored into the amorphous carbon matrix. When directly used as a binder-free anode for lithium-ion batteries, the network showed excellent electrochemical performance with high capacity, good rate capacity and reliable cycling stability. Under a current density of 0.2 A g -1 , it delivered a high reversible capacity of 875.5 mAh g -1 after 200 cycles and 1005.5 mAh g -1 after 250 cycles with a significant coulombic efficiency of 99.5%.

Functional importance of the anaphase-promoting complex-Cdh1-mediated degradation of TMAP/CKAP2 in regulation of spindle function and cytokinesis.

Science.gov (United States)

Hong, Kyung Uk; Park, Young Soo; Seong, Yeon-Sun; Kang, Dongmin; Bae, Chang-Dae; Park, Joobae

2007-05-01

Cytoskeleton-associated protein 2 (CKAP2), also known as tumor-associated microtubule-associated protein (TMAP), is a novel microtubule-associated protein that is frequently upregulated in various malignances. However, its cellular functions remain unknown. A previous study has shown that its protein level begins to increase during G(1)/S and peaks at G(2)/M, after which it decreases abruptly. Ectopic overexpression of TMAP/CKAP2 induced microtubule bundling related to increased microtubule stability. TMAP/CKAP2 overexpression also resulted in cell cycle arrest during mitosis due to a defect in centrosome separation and subsequent formation of a monopolar spindle. We also show that degradation of TMAP/CKAP2 during mitotic exit is mediated by the anaphase-promoting complex bound to Cdh1 and that the KEN box motif near the N terminus is necessary for its destruction. Compared to the wild type, expression of a nondegradable mutant of TMAP/CKAP2 significantly increased the occurrence of spindle defects and cytokinesis failure. These results suggest that TMAP/CKAP2 plays a role in the assembly and maintenance of mitotic spindles, presumably by regulating microtubule dynamics, and its destruction during mitotic exit serves an important role in the completion of cytokinesis and in the maintenance of spindle bipolarity in the next mitosis.

Eukaryotic elongation factor 2 controls TNF-α translation in LPS-induced hepatitis

Science.gov (United States)

González-Terán, Bárbara; Cortés, José R.; Manieri, Elisa; Matesanz, Nuria; Verdugo, ρngeles; Rodríguez, María E.; González-Rodríguez, ρgueda; Valverde, ρngela; Martín, Pilar; Davis, Roger J.; Sabio, Guadalupe

2012-01-01

Bacterial LPS (endotoxin) has been implicated in the pathogenesis of acute liver disease through its induction of the proinflammatory cytokine TNF-α. TNF-α is a key determinant of the outcome in a well-established mouse model of acute liver failure during septic shock. One possible mechanism for regulating TNF-α expression is through the control of protein elongation during translation, which would allow rapid cell adaptation to physiological changes. However, the regulation of translational elongation is poorly understood. We found that expression of p38γ/δ MAPK proteins is required for the elongation of nascent TNF-α protein in macrophages. The MKK3/6-p38γ/δ pathway mediated an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) kinase, which in turn promoted eEF2 activation (dephosphorylation) and subsequent TNF-α elongation. These results identify a new signaling pathway that regulates TNF-α production in LPS-induced liver damage and suggest potential cell-specific therapeutic targets for liver diseases in which TNF-α production is involved. PMID:23202732

APOBEC3G inhibits elongation of HIV-1 reverse transcripts.

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Kate N Bishop

2008-12-01

Full Text Available APOBEC3G (A3G is a host cytidine deaminase that, in the absence of Vif, restricts HIV-1 replication and reduces the amount of viral DNA that accumulates in cells. Initial studies determined that A3G induces extensive mutation of nascent HIV-1 cDNA during reverse transcription. It has been proposed that this triggers the degradation of the viral DNA, but there is now mounting evidence that this mechanism may not be correct. Here, we use a natural endogenous reverse transcriptase assay to show that, in cell-free virus particles, A3G is able to inhibit HIV-1 cDNA accumulation not only in the absence of hypermutation but also without the apparent need for any target cell factors. We find that although reverse transcription initiates in the presence of A3G, elongation of the cDNA product is impeded. These data support the model that A3G reduces HIV-1 cDNA levels by inhibiting synthesis rather than by inducing degradation.

THE SPINDLE: AN IRRADIATED DISK AND BENT PROTOSTELLAR JET IN ORION

Energy Technology Data Exchange (ETDEWEB)

Bally, John; Youngblood, Allison; Ginsburg, Adam, E-mail: John.Bally@colorado.edu, E-mail: Allison.Youngblood@colorado.edu, E-mail: Adam.Ginsburg@colorado.edu [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States)

2012-09-10

We present Hubble Space Telescope observations of a bent, pulsed Herbig-Haro jet, HH 1064, emerging from the young star Parenago 2042 embedded in the H II region NGC 1977 located about 30' north of the Orion Nebula. This outflow contains eight bow shocks in the redshifted western lobe and five bow shocks in the blueshifted eastern lobe. Shocks within a few thousand AU of the source star exhibit proper motions of {approx}160 km s{sup -1} but motions decrease with increasing distance. Parenago 2042 is embedded in a proplyd-a photoevaporating protoplanetary disk. A remarkable set of H{alpha} arcs resembling a spindle surround the redshifted (western) jet. The largest arc with a radius of 500 AU may trace the ionized edge of a circumstellar disk inclined by {approx}30 Degree-Sign . The spindle may be the photoionized edge of either a {approx}3 km s{sup -1} FUV-driven wind from the outer disk or a faster MHD-powered flow from an inner disk. The HH 1064 jet appears to be deflected north by photoablation of the south-facing side of a mostly neutral jet beam. V2412 Ori, located 1' west of Parenago 2042 drives a second bent flow, HH 1065. Both HH 1064 and 1065 are surrounded by LL Ori-type bows marking the boundary between the outflow cavity and the surrounding nebula.

Study of Contactless Power Supply for Spindle Ultrasonic Vibrator

Science.gov (United States)

Chen, T. R.; Lee, Y. L.; Liu, H. T.; Chen, S. M.; Chang, H. Z.

2017-11-01

In this study, a contactless power supply for the ultrasonic motor on the spindle is proposed. The proposed power supply is composed of a series-parallel resonant circuit and a cylindrical contactless transformer. Based on the study and rotation experiments, it can be seen that the proposed power supply can both provide a stable ac power with 25 kHz / 70 V to the ultrasonic motor. When the output power is 250 W, the efficiency of the proposed supply is 89.8 % in respectively rotation tests. When the output power is more than 150 W, the efficiency of the proposed supply is higher than 80 % within the rated output power range.

Strigolactones Stimulate Internode Elongation Independently of Gibberellins1[C][W

Science.gov (United States)

de Saint Germain, Alexandre; Ligerot, Yasmine; Dun, Elizabeth A.; Pillot, Jean-Paul; Ross, John J.; Beveridge, Christine A.; Rameau, Catherine

2013-01-01

Strigolactone (SL) mutants in diverse species show reduced stature in addition to their extensive branching. Here, we show that this dwarfism in pea (Pisum sativum) is not attributable to the strong branching of the mutants. The continuous supply of the synthetic SL GR24 via the root system using hydroponics can restore internode length of the SL-deficient rms1 mutant but not of the SL-response rms4 mutant, indicating that SLs stimulate internode elongation via RMS4. Cytological analysis of internode epidermal cells indicates that SLs control cell number but not cell length, suggesting that SL may affect stem elongation by stimulating cell division. Consequently, SLs can repress (in axillary buds) or promote (in the stem) cell division in a tissue-dependent manner. Because gibberellins (GAs) increase internode length by affecting both cell division and cell length, we tested if SLs stimulate internode elongation by affecting GA metabolism or signaling. Genetic analyses using SL-deficient and GA-deficient or DELLA-deficient double mutants, together with molecular and physiological approaches, suggest that SLs act independently from GAs to stimulate internode elongation. PMID:23943865

Elongation factor Ts directly facilitates the formation and disassembly of the Escherichia coli elongation factor Tu·GTP·aminoacyl-tRNA ternary complex.

Science.gov (United States)

Burnett, Benjamin J; Altman, Roger B; Ferrao, Ryan; Alejo, Jose L; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C

2013-05-10

Aminoacyl-tRNA (aa-tRNA) enters the ribosome in a ternary complex with the G-protein elongation factor Tu (EF-Tu) and GTP. EF-Tu·GTP·aa-tRNA ternary complex formation and decay rates are accelerated in the presence of the nucleotide exchange factor elongation factor Ts (EF-Ts). EF-Ts directly facilitates the formation and disassociation of ternary complex. This system demonstrates a novel function of EF-Ts. Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis.

Analysis of cracking potential and micro-elongation of linerboard

Directory of Open Access Journals (Sweden)

Supattra Panthai

2016-11-01

Full Text Available Folding cracks of linerboards in relation to their micro-elongation and the forming conditions were studied using an industrial linerboard machine with a top former. The experiments consisted of the study of various forming conditions by manipulating the jet/wire speed ratio to produce linerboard with differences in fiber structures that were related to the cracked and uncracked products. The results showed that changes to the jet/wire speed ratio of about 0.01–0.02 to improve the tested folding endurance in the machine direction potentially produced folding cracks in the linerboard, which indicated an ambiguous interpretation of the foldability tests. The delaminated cracked layers were found to have a high folding endurance and tensile strength, while the decrease in the micro-elongation formulated in this study was found to be related to cracking. A lower micro-elongation of about 350–500 μm/N·g was found in a range of products with folding cracks.

PLK1 regulates spindle formation kinetics and APC/C activation in mouse zygote

Czech Academy of Sciences Publication Activity Database

Baran, V.; Brzáková, Adéla; Rehák, P.; Kovaříková, V.; Šolc, Petr

2016-01-01

Roč. 24, č. 3 (2016), s. 338-345 ISSN 0967-1994 R&D Projects: GA MŠk ED2.1.00/03.0124; GA MŠk LH12057 Institutional support: RVO:67985904 Keywords : APC/C * BI2536 * live cell imaging * mouse zygote * PLK1 * securin * spindle assembly Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.053, year: 2016

On the decrease of ultimate elongation of gum elastomer by irradiation

International Nuclear Information System (INIS)

Ito, Masayuki

1986-01-01

The reason why the ultimate elongation of gum elastomer decreases by irradiation was studied. The sample used is tetrafluoroethylenepropylene copolymer vulcanized which is a heat resistant elastomer. The sample was irradiated by a electron beam at room temperature. Cross-linking predominate in the operation. (Case 1) Scission predominant condition (Case 2) was given by irradiation of Co-60 γ ray at 100 deg C. Alternative irradiation of γ ray and electron beam under above condition can keep the original cross-linking density by the appropriate choice of each of the doses. (Case 3) The three cases mentioned above involve all of the cases of radiation induced aging of elastomers. Therefor, the following explanation for three cases shows the reason why the ultimate elongation of gum elastomer decreases by irradiation. Case 1. Cross-linking predominant condition. Ultimate elongation is proportional to -0.5 power of the dose. This fact can be explicable by the model of Buche, i.e. the breaking of a short chain causes another to break and that so on throughout the whole sample. Case 2. Chain scission predominant condition. Ultimate elongation increases by irradiation for a certain dose. This fact can understand by the model of Buche. But from a certain dose ultimate elongation does not increase. In the period the structure of the sample turned to be the same structure as the low molecular weight amorphose polymer vulcanized. Case 3. Rate of cross-linking and scission is the same. The average chain length does not chainge in the condition. But the distribution of chain length became wider and wider by irradiation. The increase of short chain result the decrease in ultimate elongation. (author)

Germline-specific MATH-BTB substrate adaptor MAB1 regulates spindle length and nuclei identity in maize.

Science.gov (United States)

Juranič, Martina; Srilunchang, Kanok-orn; Krohn, Nádia Graciele; Leljak-Levanic, Dunja; Sprunck, Stefanie; Dresselhaus, Thomas

2012-12-01

Germline and early embryo development constitute ideal model systems to study the establishment of polarity, cell identity, and asymmetric cell divisions (ACDs) in plants. We describe here the function of the MATH-BTB domain protein MAB1 that is exclusively expressed in the germ lineages and the zygote of maize (Zea mays). mab1 (RNA interference [RNAi]) mutant plants display chromosome segregation defects and short spindles during meiosis that cause insufficient separation and migration of nuclei. After the meiosis-to-mitosis transition, two attached nuclei of similar identity are formed in mab1 (RNAi) mutants leading to an arrest of further germline development. Transient expression studies of MAB1 in tobacco (Nicotiana tabacum) Bright Yellow-2 cells revealed a cell cycle-dependent nuclear localization pattern but no direct colocalization with the spindle apparatus. MAB1 is able to form homodimers and interacts with the E3 ubiquitin ligase component Cullin 3a (CUL3a) in the cytoplasm, likely as a substrate-specific adapter protein. The microtubule-severing subunit p60 of katanin was identified as a candidate substrate for MAB1, suggesting that MAB1 resembles the animal key ACD regulator Maternal Effect Lethal 26 (MEL-26). In summary, our findings provide further evidence for the importance of posttranslational regulation for asymmetric divisions and germline progression in plants and identified an unstable key protein that seems to be involved in regulating the stability of a spindle apparatus regulator(s).

A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts.

Science.gov (United States)

Fox, Hannah L; Dembowski, Jill A; DeLuca, Neal A

2017-06-13

Herpes simplex virus 1 (HSV-1) genes are transcribed by cellular RNA polymerase II (RNA Pol II). While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22) function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16) was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq). The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq), we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production. IMPORTANCE HSV-1 interacts with many cellular proteins throughout productive infection. Here, we demonstrate the interaction of a viral protein, ICP22, with a subset of cellular proteins known to be involved in transcription elongation. We determined that ICP22 is required to recruit the FACT complex and other transcription

Endogenous abscisic acid as a key switch for natural variation in flooding-induced shoot elongation.

Science.gov (United States)

Chen, Xin; Pierik, Ronald; Peeters, Anton J M; Poorter, Hendrik; Visser, Eric J W; Huber, Heidrun; de Kroon, Hans; Voesenek, Laurentius A C J

2010-10-01

Elongation of leaves and stem is a key trait for survival of terrestrial plants during shallow but prolonged floods that completely submerge the shoot. However, natural floods at different locations vary strongly in duration and depth, and, therefore, populations from these locations are subjected to different selection pressure, leading to intraspecific variation. Here, we identified the signal transduction component that causes response variation in shoot elongation among two accessions of the wetland plant Rumex palustris. These accessions differed 2-fold in petiole elongation rates upon submergence, with fast elongation found in a population from a river floodplain and slow elongation in plants from a lake bank. Fast petiole elongation under water consumes carbohydrates and depends on the (inter)action of the plant hormones ethylene, abscisic acid, and gibberellic acid. We found that carbohydrate levels and dynamics in shoots did not differ between the fast and slow elongating plants, but that the level of ethylene-regulated abscisic acid in petioles, and hence gibberellic acid responsiveness of these petioles explained the difference in shoot elongation upon submergence. Since this is the exact signal transduction level that also explains the variation in flooding-induced shoot elongation among plant species (namely, R. palustris and Rumex acetosa), we suggest that natural selection results in similar modification of regulatory pathways within and between species.

Experimental results on elongation control using dynamic input allocation at FTU

International Nuclear Information System (INIS)

Varano, G.; Boncagni, L.; Galeani, S.; Granucci, G.; Vitale, V.; Zaccarian, L.

2011-01-01

We report on the experimental results related to a recently proposed control scheme for the regulation of plasma elongation using the poloidal field coils available at FTU, already used for the horizontal position control. The proposed technique allows to realize elongation regulation as a secondary task using the same poloidal coils.

Functional Importance of the Anaphase-Promoting Complex-Cdh1-Mediated Degradation of TMAP/CKAP2 in Regulation of Spindle Function and Cytokinesis▿ †

Science.gov (United States)

Hong, Kyung Uk; Park, Young Soo; Seong, Yeon-Sun; Kang, Dongmin; Bae, Chang-Dae; Park, Joobae

2007-01-01

Cytoskeleton-associated protein 2 (CKAP2), also known as tumor-associated microtubule-associated protein (TMAP), is a novel microtubule-associated protein that is frequently upregulated in various malignances. However, its cellular functions remain unknown. A previous study has shown that its protein level begins to increase during G1/S and peaks at G2/M, after which it decreases abruptly. Ectopic overexpression of TMAP/CKAP2 induced microtubule bundling related to increased microtubule stability. TMAP/CKAP2 overexpression also resulted in cell cycle arrest during mitosis due to a defect in centrosome separation and subsequent formation of a monopolar spindle. We also show that degradation of TMAP/CKAP2 during mitotic exit is mediated by the anaphase-promoting complex bound to Cdh1 and that the KEN box motif near the N terminus is necessary for its destruction. Compared to the wild type, expression of a nondegradable mutant of TMAP/CKAP2 significantly increased the occurrence of spindle defects and cytokinesis failure. These results suggest that TMAP/CKAP2 plays a role in the assembly and maintenance of mitotic spindles, presumably by regulating microtubule dynamics, and its destruction during mitotic exit serves an important role in the completion of cytokinesis and in the maintenance of spindle bipolarity in the next mitosis. PMID:17339342

Mucinous tubular and spindle cell carcinoma of kidney: A clinicopathologic study of six cases

Directory of Open Access Journals (Sweden)

Mudassar Hussain

2012-01-01

Full Text Available Background: Mucinous tubular and spindle carcinoma (MTSCC of kidney is a rare, low-grade polymorphic tumor. Recent studies have described a wide morphology spectrum of this tumor. Aim: To report the clinico-pathologic features of six cases of MTSCC of kidney. Materials and Methods: Six cases of MTSCC of kidney were studied and literature was reviewed. Immunohistochemistry was done by Envision method. Results: The age of the patients ranged from 44 to 84 years (mean 58.5 years. Four patients were males and two were females. The tumor was located in the left kidney in four cases and in the right kidney in two cases. The tumor size ranged from 4.5 to 15 cm (mean 6.4 cm. All tumors exhibited an admixture of tubules, spindle cells, and mucinous stroma in variable proportions. Tubules were predominant in five cases and spindle cells in one case. Psammomatous calcifications, papillations, and necrosis were seen in two cases. Collections of foamy histiocytes were noted in four cases. Cytoplasmic vacuoles and osseous metaplasia were seen in one case each. All cases were Fuhrman′s nuclear grade II. Five cases were of stage pT1, and one was pT3. All cases stained positive for alcian blue at pH 2.5. Immunohistochemical stain CK7 was positive in all cases and CD10 was positive in 1/1 case. All patients were alive and well at follow-up of 12-59 months (mean 33.5 months. No metastases were detected. Conclusions: We report six cases of MTSCC of kidney, a rare distinct variant of RCC, with a favorable prognosis. A male predominance was seen in our cases. MTSCC shares histologic and immunohistochemical overlap with papillary renal cell carcinoma (PRCC and cytogenetic analysis should be performed in difficult cases to avoid a misdiagnosis.

Neural mechanisms of mental schema: a triplet of delta, low beta/spindle and ripple oscillations.

Science.gov (United States)

Ohki, Takefumi; Takei, Yuichi

2018-02-06

Schemas are higher-level knowledge structures that integrate and organise lower-level representations. As internal templates, schemas are formed according to how events are perceived, interpreted and remembered. Although these higher-level units are assumed to play a fundamental role in our daily life from an early age, the neuronal basis and mechanisms of schema formation and use remain largely unknown. It is important to elucidate how the brain constructs and maintains these higher-level units. In order to examine the possible neural underpinnings of schema, we recapitulate previous work and discuss their findings related to schemas as the brain template. We specifically focused on low beta/spindle oscillations, which are assumed to be the key components of schemas, and propose that the brain template is implemented with a triplet of neural oscillations, that is delta, low beta/spindle and ripple oscillations. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Epistatic determinism of durum wheat resistance to the wheat spindle streak mosaic virus.

Science.gov (United States)

Holtz, Yan; Bonnefoy, Michel; Viader, Véronique; Ardisson, Morgane; Rode, Nicolas O; Poux, Gérard; Roumet, Pierre; Marie-Jeanne, Véronique; Ranwez, Vincent; Santoni, Sylvain; Gouache, David; David, Jacques L

2017-07-01

The resistance of durum wheat to the Wheat spindle streak mosaic virus (WSSMV) is controlled by two main QTLs on chromosomes 7A and 7B, with a huge epistatic effect. Wheat spindle streak mosaic virus (WSSMV) is a major disease of durum wheat in Europe and North America. Breeding WSSMV-resistant cultivars is currently the only way to control the virus since no treatment is available. This paper reports studies of the inheritance of WSSMV resistance using two related durum wheat populations obtained by crossing two elite cultivars with a WSSMV-resistant emmer cultivar. In 2012 and 2015, 354 recombinant inbred lines (RIL) were phenotyped using visual notations, ELISA and qPCR and genotyped using locus targeted capture and sequencing. This allowed us to build a consensus genetic map of 8568 markers and identify three chromosomal regions involved in WSSMV resistance. Two major regions (located on chromosomes 7A and 7B) jointly explain, on the basis of epistatic interactions, up to 43% of the phenotypic variation. Flanking sequences of our genetic markers are provided to facilitate future marker-assisted selection of WSSMV-resistant cultivars.

Downregulation of Protein 4.1R impairs centrosome function,bipolar spindle organization and anaphase

Energy Technology Data Exchange (ETDEWEB)

Spence, Jeffrey R.; Go, Minjoung M.; Bahmanyar, S.; Barth,A.I.M.; Krauss, Sharon Wald

2006-03-17

Centrosomes nucleate and organize interphase MTs and areinstrumental in the assembly of the mitotic bipolar spindle. Here wereport that two members of the multifunctional protein 4.1 family havedistinct distributions at centrosomes. Protein 4.1R localizes to maturecentrioles whereas 4.1G is a component of the pericentriolar matrixsurrounding centrioles. To selectively probe 4.1R function, we used RNAinterference-mediated depletion of 4.1R without decreasing 4.1Gexpression. 4.1R downregulation reduces MT anchoring and organization atinterphase and impairs centrosome separation during prometaphase.Metaphase chromosomes fail to properly condense/align and spindleorganization is aberrant. Notably 4.1R depletion causes mislocalizationof its binding partner NuMA (Nuclear Mitotic Apparatus Protein),essential for spindle pole focusing, and disrupts ninein. Duringanaphase/telophase, 4.1R-depleted cells have lagging chromosomes andaberrant MT bridges. Our data provide functional evidence that 4.1R makescrucial contributions to centrosome integrity and to mitotic spindlestructure enabling mitosis and anaphase to proceed with the coordinatedprecision required to avoid pathological events.

Gradual nerve elongation affects nerve cell bodies and neuro-muscular junctions.

Science.gov (United States)

Kazuo Ikeda, K I; Masaki Matsuda, M M; Daisuke Yamauchi, D Y; Katsuro Tomita, K T; Shigenori Tanaka, S T

2005-07-01

The purpose of this study is to clarify the reactions of the neuro-muscular junction and nerve cell body to gradual nerve elongation. The sciatic nerves of Japanese white rabbits were lengthened by 30 mm in increments of 0.8 mm/day, 2.0 mm/day and 4.0 mm/day. A scanning electron microscopic examination showed no degenerative change at the neuro-muscular junction, even eight weeks after elongation in the 4-mm group. Hence, neuro-muscular junction is not critical for predicting damage from gradual nerve elongation. There were no axon reaction cells in the 0.8-mm group, a small amount in the 2-mm group, and a large amount in the 4-mm group. The rate of growth associated protein-43 positive nerve cells was significant in the 4-mm group. Hence, the safe speed for nerve cells appeared to be 0.8-mm/day, critical speed to be 2.0-mm/day, and dangerous speed to be 4.0-mm/day in this elongation model.

Cladding axial elongation models for FRAP-T6

International Nuclear Information System (INIS)

Shah, V.N.; Carlson, E.R.; Berna, G.A.

1983-01-01

This paper presents a description of the cladding axial elongation models developed at the Idaho National Engineering Laboratory (INEL) for use by the FRAP-T6 computer code in analyzing the response of fuel rods during reactor transients in light water reactors (LWR). The FRAP-T6 code contains models (FRACAS-II subcode) that analyze the structural response of a fuel rod including pellet-cladding-mechanical-interaction (PCMI). Recently, four models were incorporated into FRACAS-II to calculate cladding axial deformation: (a) axial PCMI, (b) trapped fuel stack, (c) fuel relocation, and (d) effective fuel thermal expansion. Comparisons of cladding axial elongation measurements from two experiments with the corresponding FRAP-T6 calculations are presented

Identification of genes involved in the ACC-mediated control of root cell elongation in Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Markakis Marios

2012-11-01

Full Text Available Abstract Background Along the root axis of Arabidopsis thaliana, cells pass through different developmental stages. In the apical meristem repeated cycles of division increase the numbers of cells. Upon leaving the meristem, these cells pass the transition zone where they are physiologically and mechanically prepared to undergo subsequent rapid elongation. During the process of elongation epidermal cells increase their length by 300% in a couple of hours. When elongation ceases, the cells acquire their final size, shape and functions (in the differentiation zone. Ethylene administered as its precursor 1-aminocyclopropane-1-carboxylic acid (ACC is capable of inhibiting elongation in a concentration-dependent way. Using a microarray analysis, genes and/or processes involved in this elongation arrest are identified. Results Using a CATMA-microarray analysis performed on control and 3h ACC-treated roots, 240 differentially expressed genes were identified. Quantitative Real-Time RT-PCR analysis of the 10 most up and down regulated genes combined with literature search confirmed the accurateness of the analysis. This revealed that inhibition of cell elongation is, at least partly, caused by restricting the events that under normal growth conditions initiate elongation and by increasing the processes that normally stop cellular elongation at the end of the elongation/onset of differentiation zone. Conclusions ACC interferes with cell elongation in the Arabidopsis thaliana roots by inhibiting cells from entering the elongation process and by immediately stimulating the formation of cross-links in cell wall components, diminishing the remaining elongation capacity. From the analysis of the differentially expressed genes, it becomes clear that many genes identified in this response, are also involved in several other kind of stress responses. This suggests that many responses originate from individual elicitors, but that somewhere in the downstream

Pacemaker activity in a sensory ending with multiple encoding sites : The cat muscle spindle primary ending

NARCIS (Netherlands)

Banks, RW; Hulliger, M; Scheepstra, KA; Otten, E

1997-01-01

1. A combined physiological, histological and computer modelling study was carried out on muscle spindles of the cat tenuissimus muscle to examine whether there was any correlation between the functional interaction of putative encoding sites, operated separately by static and dynamic fusimotor

Segmentation of elongated structures in medical images

NARCIS (Netherlands)

Staal, Jozef Johannes

2004-01-01

The research described in this thesis concerns the automatic detection, recognition and segmentation of elongated structures in medical images. For this purpose techniques have been developed to detect subdimensional pointsets (e.g. ridges, edges) in images of arbitrary dimension. These

Germline-Specific MATH-BTB Substrate Adaptor MAB1 Regulates Spindle Length and Nuclei Identity in Maize[W

Science.gov (United States)

Juranić, Martina; Srilunchang, Kanok-orn; Krohn, Nádia Graciele; Leljak-Levanić, Dunja; Sprunck, Stefanie; Dresselhaus, Thomas

2012-01-01

Germline and early embryo development constitute ideal model systems to study the establishment of polarity, cell identity, and asymmetric cell divisions (ACDs) in plants. We describe here the function of the MATH-BTB domain protein MAB1 that is exclusively expressed in the germ lineages and the zygote of maize (Zea mays). mab1 (RNA interference [RNAi]) mutant plants display chromosome segregation defects and short spindles during meiosis that cause insufficient separation and migration of nuclei. After the meiosis-to-mitosis transition, two attached nuclei of similar identity are formed in mab1 (RNAi) mutants leading to an arrest of further germline development. Transient expression studies of MAB1 in tobacco (Nicotiana tabacum) Bright Yellow-2 cells revealed a cell cycle–dependent nuclear localization pattern but no direct colocalization with the spindle apparatus. MAB1 is able to form homodimers and interacts with the E3 ubiquitin ligase component Cullin 3a (CUL3a) in the cytoplasm, likely as a substrate-specific adapter protein. The microtubule-severing subunit p60 of katanin was identified as a candidate substrate for MAB1, suggesting that MAB1 resembles the animal key ACD regulator Maternal Effect Lethal 26 (MEL-26). In summary, our findings provide further evidence for the importance of posttranslational regulation for asymmetric divisions and germline progression in plants and identified an unstable key protein that seems to be involved in regulating the stability of a spindle apparatus regulator(s). PMID:23250449

Dynein Light Intermediate Chain 2 Facilitates the Metaphase to Anaphase Transition by Inactivating the Spindle Assembly Checkpoint.

Directory of Open Access Journals (Sweden)

Sagar P Mahale

Full Text Available The multi-functional molecular motor cytoplasmic dynein performs diverse essential roles during mitosis. The mechanistic importance of the dynein Light Intermediate Chain homologs, LIC1 and LIC2 is unappreciated, especially in the context of mitosis. LIC1 and LIC2 are believed to exist in distinct cytoplasmic dynein complexes as obligate subunits. LIC1 had earlier been reported to be required for metaphase to anaphase progression by inactivating the kinetochore-microtubule attachment-sensing arm of the spindle assembly checkpoint (SAC. However, the functional importance of LIC2 during mitosis remains elusive. Here we report prominent novel roles for the LIC2 subunit of cytoplasmic dynein in regulating the spindle assembly checkpoint. LIC2 depletion in mammalian cells led to prolonged metaphase arrest in the presence of an active SAC and also to stretched kinetochores, thus implicating it in SAC inactivation. Quantitative fluorescence microscopy of SAC components revealed accumulation of both attachment- and tension-sensing checkpoint proteins at metaphase kinetochores upon LIC2 depletion. These observations support a stronger and more diverse role in checkpoint inactivation for LIC2 in comparison to its close homolog LIC1. Our study uncovers a novel functional hierarchy during mitotic checkpoint inactivation between the closely related but homologous LIC subunits of cytoplasmic dynein. These subtle functional distinctions between dynein subpopulations could be exploited to study specific aspects of the spindle assembly checkpoint, which is a key mediator of fidelity in eukaryotic cell division.

Serial elongation-derotation-flexion casting for children with early-onset scoliosis.

Science.gov (United States)

Canavese, Federico; Samba, Antoine; Dimeglio, Alain; Mansour, Mounira; Rousset, Marie

2015-12-18

Various early-onset spinal deformities, particularly infantile and juvenile scoliosis (JS), still pose challenges to pediatric orthopedic surgeons. The ideal treatment of these deformities has yet to emerge, as both clinicians and surgeons still face multiple challenges including preservation of thoracic motion, spine and cage, and protection of cardiac and lung growth and function. Elongation-derotation-flexion (EDF) casting is a technique that uses a custom-made thoracolumbar cast based on a three-dimensional correction concept. EDF can control progression of the deformity and - in some cases-coax the initially-curved spine to grow straighter by acting simultaneously in the frontal, sagittal and coronal planes. Here we provide a comprehensive review of how infantile and JS can affect normal spine and thorax and how serial EDF casting can be used to manage these spinal deformities. A fresh review of the literature helps fully understand the principles of the serial EDF casting technique and the effectiveness of conservative treatment in patients with early-onset spinal deformities, particularly infantile and juvenile scolisois.

Primary spindle cell sarcoma of the prostate and 18 F-fluorodeoxyglucose-positron-emission tomography/computed tomography findings

Directory of Open Access Journals (Sweden)

Hakan Öztürk

2015-01-01

Conclusion: Spindle sarcomas of the prostate have quite aggressive nature and they have high potential to metastase. Average life expectancy is <1 year and the prognosis is poor. CTx and radiation therapy can′t yield curative effects due to poor differentiation.

Experimental and mathematical methods for representing relative surface elongation of the ACL

NARCIS (Netherlands)

Pioletti, D. P.; Heegaard, J. H.; Rakotomanana, R. L.; Leyvraz, P. F.; Blankevoort, L.

1995-01-01

The common approach to assess the stabilizing role of the ACL in the knee has been to measure the elongation of a few marked fibers in the ligament. A comparison of the relative elongation (RE) of these marked fibers between different specimens and studies is delicate due to the difficulty of

Sulfolobus tengchongensis Spindle-Shaped Virus STSV1: Virus-Host Interactions and Genomic Features

DEFF Research Database (Denmark)

Xiang, X.; Chen, L.; Huang, X

2005-01-01

of variable length (68 nm on average) at one end and is the largest of the known spindle-shaped viruses. After infecting its host, the virus multiplied rapidly to high titers (>1010 PFU/ml). Replication of the virus retarded host growth but did not cause lysis of the host cells. STSV1 did not integrate...

Drosophila Polo regulates the spindle assembly checkpoint through Mps1-dependent BubR1 phosphorylation.

Science.gov (United States)

Conde, Carlos; Osswald, Mariana; Barbosa, João; Moutinho-Santos, Tatiana; Pinheiro, Diana; Guimarães, Sofia; Matos, Irina; Maiato, Helder; Sunkel, Claudio E

2013-06-12

Maintenance of genomic stability during eukaryotic cell division relies on the spindle assembly checkpoint (SAC) that prevents mitotic exit until all chromosomes are properly attached to the spindle. Polo is a mitotic kinase proposed to be involved in SAC function, but its role has remained elusive. We demonstrate that Polo and Aurora B functional interdependency comprises a positive feedback loop that promotes Mps1 kinetochore localization and activity. Expression of constitutively active Polo restores normal Mps1 kinetochore levels even after Aurora B inhibition, highlighting a role for Polo in Mps1 recruitment to unattached kinetochores downstream of Aurora B. We also show that Mps1 kinetochore localization is required for BubR1 hyperphosphorylation and formation of the 3F3/2 phosphoepitope. This is essential to allow recruitment of Cdc20 to unattached kinetochores and the assembly of anaphase-promoting complex/cyclosome-inhibitory complexes to levels that ensure long-term SAC activity. We propose a model in which Polo controls Mps1-dependent BubR1 phosphorylation to promote Cdc20 kinetochore recruitment and sustained SAC function.

Dynamic distribution of spindlin in nucleoli, nucleoplasm and spindle from primary oocytes to mature eggs and its critical function for oocyte-to-embryo transition in gibel carp.

Science.gov (United States)

Sun, Min; Li, Zhi; Gui, Jian-Fang

2010-10-01

Spindlin (Spin) was thought as a maternal-effect factor associated with meiotic spindle. Its role for the oocyte-to-embryo transition was suggested in mouse, but its direct evidence for the function had been not obtained in other vertebrates. In this study, we used the CagSpin-specific antibody to investigate CagSpin expression pattern and distribution during oogenesis of gibel carp (Carassius auratus gibelio). First, the oocyte-specific expression pattern and dynamic distribution was revealed in nucleoli, nucleoplasm, and spindle from primary oocytes to mature eggs by immunofluorescence localization. In primary oocytes and growth stage oocytes, CagSpin accumulates in nucleoli in increasing numbers along with the oocyte growth, and its disassembly occurs in vitellogenic oocytes, which implicates that CagSpin may be a major component of a large number of nucleoli in fish growth oocytes. Then, co-localization of CagSpin and β-tubulin was revealed in meiotic spindle of mature egg, indicating that CagSpin is one spindle-associated factor. Moreover, microinjection of CagSpin-specific antibody into the fertilized eggs blocked the first cleavage, and found that the CagSpin depletion resulted in spindle assembly disturbance. Thereby, our study provided the first direct evidence for the critical oocyte-to-embryo transition function of Spin in vertebrates, and confirmed that Spin is one important maternal-effect factor that participates in oocyte growth, oocyte maturation, and oocyte-to-embryo transition.

Analysis on machine tool systems using spindle vibration monitoring for automatic tool changer

OpenAIRE

Shang-Liang Chen; Yin-Ting Cheng; Chin-Fa Su

2015-01-01

Recently, the intelligent systems of technology have become one of the major items in the development of machine tools. One crucial technology is the machinery status monitoring function, which is required for abnormal warnings and the improvement of cutting efficiency. During processing, the mobility act of the spindle unit determines the most frequent and important part such as automatic tool changer. The vibration detection system includes the development of hardware and software, such as ...

Sound propagation in elongated superfluid fermionic clouds

International Nuclear Information System (INIS)

Capuzzi, P.; Vignolo, P.; Federici, F.; Tosi, M. P.

2006-01-01

We use hydrodynamic equations to study sound propagation in a superfluid Fermi gas at zero temperature inside a strongly elongated cigar-shaped trap, with main attention to the transition from the BCS to the unitary regime. First, we treat the role of the radial density profile in the limit of a cylindrical geometry and then evaluate numerically the effect of the axial confinement in a configuration in which a hole is present in the gas density at the center of the trap. We find that in a strongly elongated trap the speed of sound in both the BCS and the unitary regime differs by a factor √(3/5) from that in a homogeneous three-dimensional superfluid. The predictions of the theory could be tested by measurements of sound-wave propagation in a setup such as that exploited by Andrews et al. [Phys. Rev. Lett. 79, 553 (1997)] for an atomic Bose-Einstein condensate

Uncovering the Molecular Machinery of the Human Spindle-An Integration of Wet and Dry Systems Biology

DEFF Research Database (Denmark)

Rojas, Ana M.; Santamaria, Anna; Malik, Rainer

2012-01-01

apparatus compared to a success rate of 35% when expert knowledge alone was used. We compare our results to the previously published MitoCheck study and see that our approach does validate some findings by this consortium. Further, we predict so-called "hidden spindle hub'', proteins whose network...

Spindle trees (Euonymus japonica Thunb.) growing in a polluted environment are less sensitive to gamma irradiation

Czech Academy of Sciences Publication Activity Database

Kim, J. K.; Cha, M.; Mukherjee, A.; Wilhelmová, Naděžda

2013-01-01

Roč. 11, č. 4 (2013), s. 233-243 ISSN 2322-3243 Institutional research plan: CEZ:AV0Z50380511 Keywords : Spindle tree * oxidative stress * ionizing radiation Subject RIV: EF - Botanics http://www.ijrr.com/browse.php?a_code=A-10-1-478&slc_lang=en&sid=1

Evaluate of the Effects of Drilling with Varying Spindle Speed Using Different Thickness of GFRP on the Damage Factor

Directory of Open Access Journals (Sweden)

Keong Woo Tze

2014-07-01

Full Text Available Composite have been widely used in industries which such as aircraft structural components, electric and electronics components, aerospace, and oil and gas fields due to their superior mechanical properties. Among machining process, drilling can be considered as one of the most important process in final machining of composite. In this research, vacuum assisted resin infusion method is use in fabricating the glass fiber reinforcement polymer samples, where different thickness of GFRP were used in the drilling process with different spindle speed. The results show that the temperature influences the damage factor of the drilling. Higher spindle speed will generate higher temperature that softens the matrix thus generating lower damage factor. The suitable drill bit temperature is between 150-200°C

Phytosterol content and the campesterol:sitosterol ratio influence cotton fiber development: role of phytosterols in cell elongation.

Science.gov (United States)

Deng, Shasha; Wei, Ting; Tan, Kunling; Hu, Mingyu; Li, Fang; Zhai, Yunlan; Ye, Shue; Xiao, Yuehua; Hou, Lei; Pei, Yan; Luo, Ming

2016-02-01

Phytosterols play an important role in plant growth and development, including cell division, cell elongation, embryogenesis, cellulose biosynthesis, and cell wall formation. Cotton fiber, which undergoes synchronous cell elongation and a large amount of cellulose synthesis, is an ideal model for the study of plant cell elongation and cell wall biogenesis. The role of phytosterols in fiber growth was investigated by treating the fibers with tridemorph, a sterol biosynthetic inhibitor. The inhibition of phytosterol biosynthesis resulted in an apparent suppression of fiber elongation in vitro or in planta. The determination of phytosterol quantity indicated that sitosterol and campesterol were the major phytosterols in cotton fibers; moreover, higher concentrations of these phytosterols were observed during the period of rapid elongation of fibers. Furthermore, the decrease and increase in campesterol:sitosterol ratio was associated with the increase and decease in speed of elongation, respectively, during the elongation stage. The increase in the ratio was associated with the transition from cell elongation to secondary cell wall synthesis. In addition, a number of phytosterol biosynthetic genes were down-regulated in the short fibers of ligon lintless-1 mutant, compared to its near-isogenic wild-type TM-1. These results demonstrated that phytosterols play a crucial role in cotton fiber development, and particularly in fiber elongation.

Disruption of spindle checkpoint function in rats following 28 days of repeated administration of renal carcinogens.

Science.gov (United States)

Kimura, Masayuki; Mizukami, Sayaka; Watanabe, Yousuke; Hasegawa-Baba, Yasuko; Onda, Nobuhiko; Yoshida, Toshinori; Shibutani, Makoto

2016-02-01

We previously reported that 28-day exposure to hepatocarcinogens that facilitate cell proliferation specifically alters the expression of G1/S checkpoint-related genes and proteins, induces aberrant early expression of ubiquitin D (UBD) at the G2 phase, and increases apoptosis in the rat liver, indicating G1/S and spindle checkpoint dysfunction. The present study aimed to determine the time of onset of carcinogen-specific cell-cycle disruption after repeated administration of renal carcinogens for up to 28 days. Rats were orally administered the renal carcinogens nitrofurantoin (NFT), 1-amino-2,4-dibromoantraquinone (ADAQ), and 1,2,3-trichloropropane (TCP) or the non-carcinogenic renal toxicants 1-chloro-2-propanol, triamterene, and carboxin for 3, 7 or 28 days. Both immunohistochemical single-molecule analysis and real-time RT-PCR analysis revealed that carcinogen-specific expression changes were not observed after 28 days of administration. However, the renal carcinogens ADAQ and TCP specifically reduced the number of cells expressing phosphorylated-histone H3 at Ser10 in both UBD(+) cells and proliferating cells, suggestive of insufficient UBD expression at the M phase and early transition of proliferating cells from the M phase, without increasing apoptosis, after 28 days of administration. In contrast, NFT, which has marginal carcinogenic potential, did not induce such cellular responses. These results suggest that it may take 28 days to induce spindle checkpoint dysfunction by renal carcinogens; however, induction of apoptosis may not be essential. Thus, induction of spindle checkpoint dysfunction may be dependent on carcinogenic potential of carcinogen examined, and marginal carcinogens may not exert sufficient responses even after 28 days of administration.

STATUS OF WOOD PROCESSING AND STORAGE IN NIGERIA

African Journals Online (AJOL)

ES Obe

[5] Dry wood has good insulating prop- erties against heat, sound, and electricity. It tends to absorb and ... Wood is primarily com- posed of hollow, elongate, spindle-shaped cells ... (F), a small core of tissue located at the cen- tre of tree stems, ...

An Actomyosin-Arf-GEF Negative Feedback Loop for Tissue Elongation under Stress.

Science.gov (United States)

West, Junior J; Zulueta-Coarasa, Teresa; Maier, Janna A; Lee, Donghoon M; Bruce, Ashley E E; Fernandez-Gonzalez, Rodrigo; Harris, Tony J C

2017-08-07

In response to a pulling force, a material can elongate, hold fast, or fracture. During animal development, multi-cellular contraction of one region often stretches neighboring tissue. Such local contraction occurs by induced actomyosin activity, but molecular mechanisms are unknown for regulating the physical properties of connected tissue for elongation under stress. We show that cytohesins, and their Arf small G protein guanine nucleotide exchange activity, are required for tissues to elongate under stress during both Drosophila dorsal closure (DC) and zebrafish epiboly. In Drosophila, protein localization, laser ablation, and genetic interaction studies indicate that the cytohesin Steppke reduces tissue tension by inhibiting actomyosin activity at adherens junctions. Without Steppke, embryogenesis fails, with epidermal distortions and tears resulting from myosin misregulation. Remarkably, actomyosin network assembly is necessary and sufficient for local Steppke accumulation, where live imaging shows Steppke recruitment within minutes. This rapid negative feedback loop provides a molecular mechanism for attenuating the main tension generator of animal tissues. Such attenuation relaxes tissues and allows orderly elongation under stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temporal and SUMO-specific SUMOylation contribute to the dynamics of Polo-like kinase 1 (PLK1) and spindle integrity during mouse oocyte meiosis.

Science.gov (United States)

Feitosa, Weber Beringui; Hwang, KeumSil; Morris, Patricia L

2018-02-15

During mammalian meiosis, Polo-like kinase 1 (PLK1) is essential during cell cycle progression. In oocyte maturation, PLK1 expression is well characterized but timing of posttranslational modifications regulating its activity and subcellular localization are less clear. Small ubiquitin-related modifier (SUMO) posttranslational modifier proteins have been detected in mammalian gametes but their precise function during gametogenesis is largely unknown. In the present paper we report for mouse oocytes that both PLK1 and phosphorylated PLK1 undergo SUMOylation in meiosis II (MII) oocytes using immunocytochemistry, immunoprecipitation and in vitro SUMOylation assays. At MII, PLK1 is phosphorylated at threonine-210 and serine-137. MII oocyte PLK1 and phosphorylated PLK1 undergo SUMOylation by SUMO-1, -2 and -3 as shown by individual in vitro assays. Using these assays, forms of phosphorylated PLK1 normalized to PLK1 increased significantly and correlated with SUMOylated PLK1 levels. During meiotic progression and maturation, SUMO-1-SUMOylation of PLK1 is involved in spindle formation whereas SUMO-2/3-SUMOylation may regulate PLK1 activity at kinetochore-spindle attachment sites. Microtubule integrity is required for PLK1 localization with SUMO-1 but not with SUMO-2/3. Inhibition of SUMOylation disrupts proper meiotic bipolar spindle organization and spindle-kinetochore attachment. The data show that both temporal and SUMO-specific-SUMOylation play important roles in orchestrating functional dynamics of PLK1 during mouse oocyte meiosis, including subcellular compartmentalization. Copyright © 2018 Elsevier Inc. All rights reserved.

Directional errors of movements and their correction in a discrete tracking task. [pilot reaction time and sensorimotor performance

Science.gov (United States)

Jaeger, R. J.; Agarwal, G. C.; Gottlieb, G. L.

1978-01-01

Subjects can correct their own errors of movement more quickly than they can react to external stimuli by using three general categories of feedback: (1) knowledge of results, primarily visually mediated; (2) proprioceptive or kinaesthetic such as from muscle spindles and joint receptors, and (3) corollary discharge or efference copy within the central nervous system. The effects of these feedbacks on simple reaction time, choice reaction time, and error correction time were studied in four normal human subjects. The movement used was plantarflexion and dorsiflexion of the ankle joint. The feedback loops were modified, by changing the sign of the visual display to alter the subject's perception of results, and by applying vibration at 100 Hz simultaneously to both the agonist and antagonist muscles of the ankle joint. The central processing was interfered with when the subjects were given moderate doses of alcohol (blood alcohol concentration levels of up to 0.07%). Vibration and alcohol increase both the simple and choice reaction times but not the error correction time.

Functional, electrophysiological recoveries of rats with sciatic nerve lesions following transplantation of elongated DRG cells.

Science.gov (United States)

Dayawansa, Samantha; Zhang, Jun; Shih, Chung-Hsuan; Tharakan, Binu; Huang, Jason H

2016-04-01

Functional data are essential when confirming the efficacy of elongated dorsal root ganglia (DRG) cells as a substitute for autografting. We present the quantitative functional motor, electrophysiological findings of engineered DRG recipients for the first time. Elongated DRG neurons and autografts were transplanted to bridge 1-cm sciatic nerve lesions of Sprague Dawley (SD) rats. Motor recoveries of elongated DRG recipients (n=9), autograft recipients (n=9), unrepaired rats (n=9) and intact rats (n=6) were investigated using the angle board challenge test following 16 weeks of recovery. Electrophysiology studies were conducted to assess the functional recovery at 16 weeks. In addition, elongated DRGs were subjected to histology assessments. At threshold levels (35° angle) of the angle board challenge test, the autograft recipients', DRG recipients' and unrepaired group's performances were equal to each other and were less than the intact group (pDRG recipients' performance was similar to both the intact group and the autograft nerve recipients, and was better (pDRG constructs had intact signal transmission when recorded over the lesion, while the unrepaired rats did not. It was observed that elongated DRG neurons closely resembled an autograft during histological assessments. Performances of autograft and elongated DRG construct recipients were similar. Elongated DRG neurons should be further investigated as a substitute for autografting.

Overexpression of rice LRK1 restricts internode elongation by down-regulating OsKO2.

Science.gov (United States)

Yang, Mengfei; Qi, Weiwei; Sun, Fan; Zha, Xiaojun; Chen, Mingluan; Huang, Yunqing; Feng, Yu-Qi; Yang, Jinshui; Luo, Xiaojin

2013-01-01

Rice (Oryza sativa) has the potential to undergo rapid internodal elongation which determines plant height. Gibberellin is involved in internode elongation. Leucine-rich repeat receptor-like kinases (LRR-RLKs) are the largest subfamily of transmembrane receptor-like kinases in plants. LRR-RLKs play important functions in mediating a variety of cellular processes and regulating responses to environmental signals. LRK1, a PSK receptor homolog, is a member of the LRR-RLK family. In the present study, differences in ectopic expression of LRK1 were consistent with extent of rice internode elongation. Analyses of gene expression demonstrated that LRK1 restricts gibberellin biosynthesis during the internode elongation process by down-regulation of the gibberellin biosynthetic gene coding for ent-kaurene oxidase.

The relationship between cell killing, chromosome aberrations, spindle defects, and mitotic delay in mouse lymphoma cells of differential sensitivity to X-rays

International Nuclear Information System (INIS)

Scott, D.; Zampetti-Bosseler, F.

1980-01-01

A study has been made of the effects of x radiation on an ultrasensitive subline of L5178Y mouse lymphoma cells. It has been shown that at survival levels above about 20 per cent, chromosome structural aberrations which lead to bridges and fragments at anaphase are about four times more frequent than spindle defects. The results demonstrated the higher frequency of structural aberrations and spindle defects, and the greater mitotic delay in the X-ray-sensitive than in the X-ray-resistant cell line. A model is proposed which causally relates these end-points to cell killing and DNA repair. (author)

Cellular angiofibroma: analysis of 25 cases emphasizing its relationship to spindle cell lipoma and mammary-type myofibroblastoma

NARCIS (Netherlands)

Flucke, U.E.; Krieken, J.H. van; Mentzel, T.

2011-01-01

Cellular angiofibroma represents a rare benign mesenchymal tumor, occurring mainly in the superficial soft tissue of the genital region. The involvement of 13q14 in some cases confirmed the morphological suggested link with spindle cell lipoma and mammary-type myofibroblastoma. We analyzed the

Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning.

Science.gov (United States)

Kojo, Kei H; Yasuhara, Hiroki; Hasezawa, Seiichiro

2014-01-01

Precise division plane determination is essential for plant development. At metaphase, a dense actin microfilament meshwork appears on both sides of the cell center, forming a characteristic cortical actin microfilament twin peak pattern in BY-2 cells. We previously reported a strong correlation between altered cortical actin microfilament patterning and an oblique mitotic spindle orientation, implying that these actin microfilament twin peaks play a role in the regulation of mitotic spindle orientation. In the present study, time-sequential observation was used to reveal the progression from oblique phragmoplast to oblique cell plate orientation in cells with altered cortical actin microfilament patterning. In contrast to cells with normal actin microfilament twin peaks, oblique phragmoplast reorientation was rarely observed in cells with altered cortical actin microfilament patterning. These results support the important roles of cortical actin microfilament patterning in division plane orientation.

1,8-cineole inhibits both proliferation and elongation of BY-2 cultured tobacco cells.

Science.gov (United States)

Yoshimura, Hiroko; Sawai, Yu; Tamotsu, Satoshi; Sakai, Atsushi

2011-03-01

Volatile monoterpenes such as 1,8-cineole inhibit the growth of Brassica campestris seedlings in a dose-dependent manner, and the growth-inhibitory effects are more severe for roots than hypocotyls. The preferential inhibition of root growth may be explained if the compounds inhibit cell proliferation more severely than cell elongation because root growth requires both elongation and proliferation of the constituent cells, whereas hypocotyl growth depends exclusively on elongation of existing cells. In order to examine this possibility, BY-2 suspension-cultured tobacco (Nicotiana tabacum) cells were treated with 1,8-cineole, and the inhibitory effects on cell proliferation and on cell elongation were assessed quantitatively. Treatment with 1,8-cineole lowered both the mitotic index and elongation of the cells in a dose-dependent manner, and the half-maximal inhibitory concentration (IC₅₀) for cell elongation was lower than that for cell proliferation. Moreover, 1,8-cineole also inhibited starch synthesis, with IC₅₀ lower than that for cell proliferation. Thus, the inhibitory effects of 1,8-cineole were not specific to cell proliferation; rather, 1,8-cineole seemed inhibitory to a variety of physiological activities when it was in direct contact with target cells. Based on these results, possible mechanisms for the mode of action of 1,8-cineole and for its preferential inhibition on root growth are discussed.

Contribution of Cell Elongation to the Biofilm Formation of Pseudomonas aeruginosa during Anaerobic Respiration

Science.gov (United States)

Park, Yongjin; Yoon, Sang Sun

2011-01-01

Pseudomonas aeruginosa, a gram-negative bacterium of clinical importance, forms more robust biofilm during anaerobic respiration, a mode of growth presumed to occur in abnormally thickened mucus layer lining the cystic fibrosis (CF) patient airway. However, molecular basis behind this anaerobiosis-triggered robust biofilm formation is not clearly defined yet. Here, we identified a morphological change naturally accompanied by anaerobic respiration in P. aeruginosa and investigated its effect on the biofilm formation in vitro. A standard laboratory strain, PAO1 was highly elongated during anaerobic respiration compared with bacteria grown aerobically. Microscopic analysis demonstrated that cell elongation likely occurred as a consequence of defective cell division. Cell elongation was dependent on the presence of nitrite reductase (NIR) that reduces nitrite (NO2 −) to nitric oxide (NO) and was repressed in PAO1 in the presence of carboxy-PTIO, a NO antagonist, demonstrating that cell elongation involves a process to respond to NO, a spontaneous byproduct of the anaerobic respiration. Importantly, the non-elongated NIR-deficient mutant failed to form biofilm, while a mutant of nitrate reductase (NAR) and wild type PAO1, both of which were highly elongated, formed robust biofilm. Taken together, our data reveal a role of previously undescribed cell biological event in P. aeruginosa biofilm formation and suggest NIR as a key player involved in such process. PMID:21267455

Significant enhancement by biochar of caproate production via chain elongation.

Science.gov (United States)

Liu, Yuhao; He, Pinjing; Shao, Liming; Zhang, Hua; Lü, Fan

2017-08-01

In this study, biochar was introduced into a chain elongation system to enhance the bioproduction of caproate and caprylate. The concentration of caproate increased to 21.1 g/L upon the addition of biochar, which is the highest level of caproate reported for such a system to date when ethanol was used as electron donor. The addition of biochar created a tougher system with more stable microorganism community structure for chain elongation, in which no obvious inhibition by products or substrates was observed, moreover, the lag phase was reduced 2.3-fold compared to the system without biochar. These reinforcement effect of biochar are attributed to the enhanced conductivity due to the significant enrichment of functional microorganisms via the microbial network surrounding smaller biochar particles, and via the adsorption on the rough surfaces or pores of larger particles, which facilitated electron transfer. Higher amounts of extracellular polymer substances and higher conductivity induced by biochar could contribute to the reinforcement effect in chain elongation. Copyright © 2017 Elsevier Ltd. All rights reserved.

pix-1 controls early elongation in parallel with mel-11 and let-502 in Caenorhabditis elegans.

Science.gov (United States)

Martin, Emmanuel; Harel, Sharon; Nkengfac, Bernard; Hamiche, Karim; Neault, Mathieu; Jenna, Sarah

2014-01-01

Cell shape changes are crucial for metazoan development. During Caenorhabditis elegans embryogenesis, epidermal cell shape changes transform ovoid embryos into vermiform larvae. This process is divided into two phases: early and late elongation. Early elongation involves the contraction of filamentous actin bundles by phosphorylated non-muscle myosin in a subset of epidermal (hypodermal) cells. The genes controlling early elongation are associated with two parallel pathways. The first one involves the rho-1/RHOA-specific effector let-502/Rho-kinase and mel-11/myosin phosphatase regulatory subunit. The second pathway involves the CDC42/RAC-specific effector pak-1. Late elongation is driven by mechanotransduction in ventral and dorsal hypodermal cells in response to body-wall muscle contractions, and involves the CDC42/RAC-specific Guanine-nucleotide Exchange Factor (GEF) pix-1, the GTPase ced-10/RAC and pak-1. In this study, pix-1 is shown to control early elongation in parallel with let-502/mel-11, as previously shown for pak-1. We show that pix-1, pak-1 and let-502 control the rate of elongation, and the antero-posterior morphology of the embryos. In particular, pix-1 and pak-1 are shown to control head, but not tail width, while let-502 controls both head and tail width. This suggests that let-502 function is required throughout the antero-posterior axis of the embryo during early elongation, while pix-1/pak-1 function may be mostly required in the anterior part of the embryo. Supporting this hypothesis we show that low pix-1 expression level in the dorsal-posterior hypodermal cells is required to ensure high elongation rate during early elongation.

Interplay between DNA supercoiling and transcription elongation.

Science.gov (United States)

Ma, Jie; Wang, Michelle

2014-01-01

Transcription-coupled DNA supercoiling has been shown to be an important regulator of transcription that is broadly present in the cell. Here we review experimental work which shows that RNA polymerase is a powerful torsional motor that can alter DNA topology and structure, and DNA supercoiling in turn directly affects transcription elongation.

Transcription elongation. Heterogeneous tracking of RNA polymerase and its biological implications.

Science.gov (United States)

Imashimizu, Masahiko; Shimamoto, Nobuo; Oshima, Taku; Kashlev, Mikhail

2014-01-01

Regulation of transcription elongation via pausing of RNA polymerase has multiple physiological roles. The pausing mechanism depends on the sequence heterogeneity of the DNA being transcribed, as well as on certain interactions of polymerase with specific DNA sequences. In order to describe the mechanism of regulation, we introduce the concept of heterogeneity into the previously proposed alternative models of elongation, power stroke and Brownian ratchet. We also discuss molecular origins and physiological significances of the heterogeneity.

A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts

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Hannah L. Fox

2017-06-01

Full Text Available Herpes simplex virus 1 (HSV-1 genes are transcribed by cellular RNA polymerase II (RNA Pol II. While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22 function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16 was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq. The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq, we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production.

Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

Energy Technology Data Exchange (ETDEWEB)

Yu, Yueyang [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States); Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States)

2012-10-10

The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore-microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope.

Science.gov (United States)

Wang, Peng; Behan, Gavin; Kirkland, Angus I; Nellist, Peter D; Cosgriff, Eireann C; D'Alfonso, Adrian J; Morgan, Andrew J; Allen, Leslie J; Hashimoto, Ayako; Takeguchi, Masaki; Mitsuishi, Kazutaka; Shimojo, Masayuki

2011-06-01

Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored. Copyright © 2010 Elsevier B.V. All rights reserved.

Life Cycle Characterization of Sulfolobus Monocaudavirus 1, an Extremophilic Spindle-Shaped Virus with Extracellular Tail Development.

Science.gov (United States)

Uldahl, Kristine B; Jensen, Signe B; Bhoobalan-Chitty, Yuvaraj; Martínez-Álvarez, Laura; Papathanasiou, Pavlos; Peng, Xu

2016-06-15

We provide here, for the first time, insights into the initial infection stages of a large spindle-shaped archaeal virus and explore the following life cycle events. Our observations suggest that Sulfolobus monocaudavirus 1 (SMV1) exhibits a high adsorption rate and that virions adsorb to the host cells via three distinct attachment modes: nosecone association, body association, and body/tail association. In the body/tail association mode, the entire virion, including the tail(s), aligns to the host cell surface and the main body is greatly flattened, suggesting a possible fusion entry mechanism. Upon infection, the intracellular replication cycle lasts about 8 h, at which point the virions are released as spindle-shaped tailless particles. Replication of the virus retarded host growth but did not cause lysis of the host cells. Once released from the host and at temperatures resembling that of its natural habitat, SMV1 starts developing one or two tails. This exceptional property of undergoing a major morphological development outside, and independently of, the host cell has been reported only once before for the related Acidianus two-tailed virus. Here, we show that SMV1 can develop tails of more than 900 nm in length, more than quadrupling the total virion length. Very little is known about the initial life cycle stages of viruses infecting hosts of the third domain of life, Archaea This work describes the first example of an archaeal virus employing three distinct association modes. The virus under study, Sulfolobus monocaudavirus 1, is a representative of the large spindle-shaped viruses that are frequently found in acidic hot springs. The results described here will add valuable knowledge about Archaea, the least studied domain in the virology field. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

The effect of heat and radiation on the initiation and elongation processes of DNA synthesis

International Nuclear Information System (INIS)

Davies, R.C.; Bowden, G.T.; Cress, A.E.

1983-01-01

The pH step alkaline elution and alkaline sucrose gradient techniques were utilized to evaluate alterations in DNA replication (initiation and elongation) induced by heat and low dose X-irradiation in synchronized Chinese hamster ovary cells. The initiation and elongation processes of DNA synthesis were radioresistant at the G 1 /S boundary (4 hours after mitosis) while in mid S phase (9 hours after mitosis) DNA initiation and elongation were sensitive to X-irradiation. The initiation and elongation processes of DNA synthesis which were radiation resistant at the G 1 /S boundary could be inhibited by a hyperthermia treatment (43 0 C for 1 hour beginning at 4 hours after mitosis). The impairment of initiation in the heated cells was maintained through late S phase while that of elongation was reversible as judged by full recovery at 15 hours after mitosis. These data suggest that the known synergistic lethality of heat and radiation may be mediated by an impairment of initiation of DNA synthesis. (author)

Codon usage regulates protein structure and function by affecting translation elongation speed in Drosophila cells.

Science.gov (United States)

Zhao, Fangzhou; Yu, Chien-Hung; Liu, Yi

2017-08-21

Codon usage biases are found in all eukaryotic and prokaryotic genomes and have been proposed to regulate different aspects of translation process. Codon optimality has been shown to regulate translation elongation speed in fungal systems, but its effect on translation elongation speed in animal systems is not clear. In this study, we used a Drosophila cell-free translation system to directly compare the velocity of mRNA translation elongation. Our results demonstrate that optimal synonymous codons speed up translation elongation while non-optimal codons slow down translation. In addition, codon usage regulates ribosome movement and stalling on mRNA during translation. Finally, we show that codon usage affects protein structure and function in vitro and in Drosophila cells. Together, these results suggest that the effect of codon usage on translation elongation speed is a conserved mechanism from fungi to animals that can affect protein folding in eukaryotic organisms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level.

Science.gov (United States)

Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

2007-06-17

Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced. Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level

Directory of Open Access Journals (Sweden)

Derbyshire Paul

2007-06-01

Full Text Available Abstract Background Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. Results We present evidence that the degree of pectin methyl-esterification (DE% limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1 from Aspergillus aculeatus, then hypocotyl elongation is reduced. Conclusion Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

When the genome plays dice: circumvention of the spindle assembly checkpoint and near-random chromosome segregation in multipolar cancer cell mitoses.

Science.gov (United States)

Gisselsson, David; Håkanson, Ulf; Stoller, Patrick; Marti, Dominik; Jin, Yuesheng; Rosengren, Anders H; Stewénius, Ylva; Kahl, Fredrik; Panagopoulos, Ioannis

2008-04-02

Normal cell division is coordinated by a bipolar mitotic spindle, ensuring symmetrical segregation of chromosomes. Cancer cells, however, occasionally divide into three or more directions. Such multipolar mitoses have been proposed to generate genetic diversity and thereby contribute to clonal evolution. However, this notion has been little validated experimentally. Chromosome segregation and DNA content in daughter cells from multipolar mitoses were assessed by multiphoton cross sectioning and fluorescence in situ hybridization in cancer cells and non-neoplastic transformed cells. The DNA distribution resulting from multipolar cell division was found to be highly variable, with frequent nullisomies in the daughter cells. Time-lapse imaging of H2B/GFP-labelled multipolar mitoses revealed that the time from the initiation of metaphase to the beginning of anaphase was prolonged and that the metaphase plates often switched polarity several times before metaphase-anaphase transition. The multipolar metaphase-anaphase transition was accompanied by a normal reduction of cellular cyclin B levels, but typically occurred before completion of the normal separase activity cycle. Centromeric AURKB and MAD2 foci were observed frequently to remain on the centromeres of multipolar ana-telophase chromosomes, indicating that multipolar mitoses were able to circumvent the spindle assembly checkpoint with some sister chromatids remaining unseparated after anaphase. Accordingly, scoring the distribution of individual chromosomes in multipolar daughter nuclei revealed a high frequency of nondisjunction events, resulting in a near-binomial allotment of sister chromatids to the daughter cells. The capability of multipolar mitoses to circumvent the spindle assembly checkpoint system typically results in a near-random distribution of chromosomes to daughter cells. Spindle multipolarity could thus be a highly efficient generator of genetically diverse minority clones in transformed cell

When the genome plays dice: circumvention of the spindle assembly checkpoint and near-random chromosome segregation in multipolar cancer cell mitoses.

Directory of Open Access Journals (Sweden)

David Gisselsson

Full Text Available BACKGROUND: Normal cell division is coordinated by a bipolar mitotic spindle, ensuring symmetrical segregation of chromosomes. Cancer cells, however, occasionally divide into three or more directions. Such multipolar mitoses have been proposed to generate genetic diversity and thereby contribute to clonal evolution. However, this notion has been little validated experimentally. PRINCIPAL FINDINGS: Chromosome segregation and DNA content in daughter cells from multipolar mitoses were assessed by multiphoton cross sectioning and fluorescence in situ hybridization in cancer cells and non-neoplastic transformed cells. The DNA distribution resulting from multipolar cell division was found to be highly variable, with frequent nullisomies in the daughter cells. Time-lapse imaging of H2B/GFP-labelled multipolar mitoses revealed that the time from the initiation of metaphase to the beginning of anaphase was prolonged and that the metaphase plates often switched polarity several times before metaphase-anaphase transition. The multipolar metaphase-anaphase transition was accompanied by a normal reduction of cellular cyclin B levels, but typically occurred before completion of the normal separase activity cycle. Centromeric AURKB and MAD2 foci were observed frequently to remain on the centromeres of multipolar ana-telophase chromosomes, indicating that multipolar mitoses were able to circumvent the spindle assembly checkpoint with some sister chromatids remaining unseparated after anaphase. Accordingly, scoring the distribution of individual chromosomes in multipolar daughter nuclei revealed a high frequency of nondisjunction events, resulting in a near-binomial allotment of sister chromatids to the daughter cells. CONCLUSION: The capability of multipolar mitoses to circumvent the spindle assembly checkpoint system typically results in a near-random distribution of chromosomes to daughter cells. Spindle multipolarity could thus be a highly efficient

Stereotypical reaching movements of the octopus involve both bend propagation and arm elongation.

Science.gov (United States)

Hanassy, S; Botvinnik, A; Flash, T; Hochner, B

2015-05-13

The bend propagation involved in the stereotypical reaching movement of the octopus arm has been extensively studied. While these studies have analyzed the kinematics of bend propagation along the arm during its extension, possible length changes have been ignored. Here, the elongation profiles of the reaching movements of Octopus vulgaris were assessed using three-dimensional reconstructions. The analysis revealed that, in addition to bend propagation, arm extension movements involve elongation of the proximal part of the arm, i.e., the section from the base of the arm to the propagating bend. The elongations are quite substantial and highly variable, ranging from an average strain along the arm of -0.12 (i.e. shortening) up to 1.8 at the end of the movement (0.57 ± 0.41, n = 64 movements, four animals). Less variability was discovered in an additional set of experiments on reaching movements (0.64 ± 0.28, n = 30 movements, two animals), where target and octopus positions were kept more stationary. Visual observation and subsequent kinematic analysis suggest that the reaching movements can be broadly segregated into two groups. The first group involves bend propagation beginning at the base of the arm and propagating towards the arm tip. In the second, the bend is formed or present more distally and reaching is achieved mainly by elongation and straightening of the segment proximal to the bend. Only in the second type of movements is elongation significantly positively correlated with the distance of the bend from the target. We suggest that reaching towards a target is generated by a combination of both propagation of a bend along the arm and arm elongation. These two motor primitives may be combined to create a broad spectrum of reaching movements. The dynamical model, which recapitulates the biomechanics of the octopus muscular hydrostatic arm, suggests that achieving the observed elongation requires an extremely low ratio of longitudinal to transverse muscle

The conserved Wdr8-hMsd1/SSX2IP complex localises to the centrosome and ensures proper spindle length and orientation

International Nuclear Information System (INIS)

Hori, Akiko; Morand, Agathe; Ikebe, Chiho; Frith, David; Snijders, Ambrosius P.; Toda, Takashi

2015-01-01

The centrosome plays a pivotal role in a wide range of cellular processes and its dysfunction is causally linked to many human diseases including cancer and developmental and neurological disorders. This organelle contains more than one hundred components, and yet many of them remain uncharacterised. Here we identified a novel centrosome protein Wdr8, based upon the structural conservation of the fission yeast counterpart. We showed that Wdr8 constitutively localises to the centrosome and super resolution microscopy uncovered that this protein is enriched at the proximal end of the mother centriole. Furthermore, we identified hMsd1/SSX2IP, a conserved spindle anchoring protein, as one of Wdr8 interactors by mass spectrometry. Wdr8 formed a complex and partially colocalised with hMsd1/SSX2IP. Intriguingly, knockdown of Wdr8 or hMsd1/SSX2IP displayed very similar mitotic defects, in which spindle microtubules became shortened and misoriented. Indeed, Wdr8 depletion resulted in the reduced recruitment of hMsd1/SSX2IP to the mitotic centrosome, though the converse is not true. Together, we propose that the conserved Wdr8-hMsd1/SSX2IP complex plays a critical role in controlling proper spindle length and orientation. - Highlights: • Human Wdr8 is a centrosomal protein enriched in the proximal end of the centriole. • Wdr8 and hMsd1/SSX2IP form a complex conserved in fungi. • Depletion of Wdr8 results in shorter, tilted spindle microtubules. • Depletion phenotypes of Wdr8 are very similar to those of hMsd1/SSX2IP knockdown.

The conserved Wdr8-hMsd1/SSX2IP complex localises to the centrosome and ensures proper spindle length and orientation

Energy Technology Data Exchange (ETDEWEB)

Hori, Akiko; Morand, Agathe; Ikebe, Chiho; Frith, David; Snijders, Ambrosius P.; Toda, Takashi, E-mail: takashi-toda@hiroshima-u.ac.jp

2015-12-04

The centrosome plays a pivotal role in a wide range of cellular processes and its dysfunction is causally linked to many human diseases including cancer and developmental and neurological disorders. This organelle contains more than one hundred components, and yet many of them remain uncharacterised. Here we identified a novel centrosome protein Wdr8, based upon the structural conservation of the fission yeast counterpart. We showed that Wdr8 constitutively localises to the centrosome and super resolution microscopy uncovered that this protein is enriched at the proximal end of the mother centriole. Furthermore, we identified hMsd1/SSX2IP, a conserved spindle anchoring protein, as one of Wdr8 interactors by mass spectrometry. Wdr8 formed a complex and partially colocalised with hMsd1/SSX2IP. Intriguingly, knockdown of Wdr8 or hMsd1/SSX2IP displayed very similar mitotic defects, in which spindle microtubules became shortened and misoriented. Indeed, Wdr8 depletion resulted in the reduced recruitment of hMsd1/SSX2IP to the mitotic centrosome, though the converse is not true. Together, we propose that the conserved Wdr8-hMsd1/SSX2IP complex plays a critical role in controlling proper spindle length and orientation. - Highlights: • Human Wdr8 is a centrosomal protein enriched in the proximal end of the centriole. • Wdr8 and hMsd1/SSX2IP form a complex conserved in fungi. • Depletion of Wdr8 results in shorter, tilted spindle microtubules. • Depletion phenotypes of Wdr8 are very similar to those of hMsd1/SSX2IP knockdown.

Effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhi [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Department of Bone and Joint Surgery, The affiliated hospital of Luzhou Medical College, Luzhou 646000 (China); Qing, Quan [Sichuan College of Traditional Chinese Medicine, Mianyang 621000 (China); Regenerative Medicine Research Center, West China Hospital of Sichuan University, Chengdu 610041 (China); Chen, Xi; Liu, Cheng-Jun; Luo, Jing-Cong [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Hu, Jin-Lian [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Qin, Ting-Wu, E-mail: tingwuqin@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China)

2016-12-01

Highlights: • The shapes of tenocytes varied when seeded on different surface of scaffolds. • Tenocytes were flat on smooth surface and spindle on micro-grooved surface. • Tenocytes were ellipse or spindle on porous surface. • Tenocytes got varying adhesion shape and elongation index on varying surfaces. • The tenocyte survival on porous surface was superior to the other two groups. - Abstract: The purpose of this study was to investigate the effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs. Tenocytes were obtained from tail tendons of rats. Polydimethylsiloxane (PDMS) was used to fabricate three types of scaffolds with varying surface morphological characteristics, i.e., smooth, micro-grooved, and porous surfaces, respectively. The tenocytes were seeded on the surfaces of the scaffolds to form tenocyte-scaffold constructs. The constructs were cryopreserved in a vitreous cryoprotectant (CPA) with a multi-step protocol. The cell adhesion to scaffolds was observed with electronic scanning microscopy (SEM). The elongation index of the living tenocytes and ratio of live/dead cell number were examined based on a live/dead dual fluorescent staining technique, and the survival rate of tenocytes was studied with flow cytometry (FC). The results showed the shapes of tenocytes varied between the different groups: flat or polygonal (on smooth surface), spindle (on micro-grooved surface), and spindle or ellipse (on porous surface). After thawing, the porous surface got the most living tenocytes and a higher survival rate, suggesting its potential application for vitreous cryopreservation of engineered tendon constructs.

A morphospace for reef fishes: elongation is the dominant axis of body shape evolution.

Directory of Open Access Journals (Sweden)

Thomas Claverie

Full Text Available Tropical reef fishes are widely regarded as being perhaps the most morphologically diverse vertebrate assemblage on earth, yet much remains to be discovered about the scope and patterns of this diversity. We created a morphospace of 2,939 species spanning 56 families of tropical Indo-Pacific reef fishes and established the primary axes of body shape variation, the phylogenetic consistency of these patterns, and whether dominant patterns of shape change can be accomplished by diverse underlying changes. Principal component analysis showed a major axis of shape variation that contrasts deep-bodied species with slender, elongate forms. Furthermore, using custom methods to compare the elongation vector (axis that maximizes elongation deformation and the main vector of shape variation (first principal component for each family in the morphospace, we showed that two thirds of the families diversify along an axis of body elongation. Finally, a comparative analysis using a principal coordinate analysis based on the angles among first principal component vectors of each family shape showed that families accomplish changes in elongation with a wide range of underlying modifications. Some groups such as Pomacentridae and Lethrinidae undergo decreases in body depth with proportional increases in all body regions, while other families show disproportionate changes in the length of the head (e.g., Labridae, the trunk or caudal region in all combinations (e.g., Pempheridae and Pinguipedidae. In conclusion, we found that evolutionary changes in body shape along an axis of elongation dominates diversification in reef fishes. Changes in shape on this axis are thought to have immediate implications for swimming performance, defense from gape limited predators, suction feeding performance and access to some highly specialized habitats. The morphological modifications that underlie changes in elongation are highly diverse, suggesting a role for a range of

A Morphospace for Reef Fishes: Elongation Is the Dominant Axis of Body Shape Evolution

Science.gov (United States)

Claverie, Thomas; Wainwright, Peter C.

2014-01-01

Tropical reef fishes are widely regarded as being perhaps the most morphologically diverse vertebrate assemblage on earth, yet much remains to be discovered about the scope and patterns of this diversity. We created a morphospace of 2,939 species spanning 56 families of tropical Indo-Pacific reef fishes and established the primary axes of body shape variation, the phylogenetic consistency of these patterns, and whether dominant patterns of shape change can be accomplished by diverse underlying changes. Principal component analysis showed a major axis of shape variation that contrasts deep-bodied species with slender, elongate forms. Furthermore, using custom methods to compare the elongation vector (axis that maximizes elongation deformation) and the main vector of shape variation (first principal component) for each family in the morphospace, we showed that two thirds of the families diversify along an axis of body elongation. Finally, a comparative analysis using a principal coordinate analysis based on the angles among first principal component vectors of each family shape showed that families accomplish changes in elongation with a wide range of underlying modifications. Some groups such as Pomacentridae and Lethrinidae undergo decreases in body depth with proportional increases in all body regions, while other families show disproportionate changes in the length of the head (e.g., Labridae), the trunk or caudal region in all combinations (e.g., Pempheridae and Pinguipedidae). In conclusion, we found that evolutionary changes in body shape along an axis of elongation dominates diversification in reef fishes. Changes in shape on this axis are thought to have immediate implications for swimming performance, defense from gape limited predators, suction feeding performance and access to some highly specialized habitats. The morphological modifications that underlie changes in elongation are highly diverse, suggesting a role for a range of developmental processes

Analysis of the failure of a vacuum spin-pit drive turbine spindle shaft

OpenAIRE

Pettitt, Jason M.

2005-01-01

The Naval Postgraduate School's Rotor Spin Research Facility experienced a failure in the Spring of 2005 in which the rotor dropped from the drive turbine and caused extensive damage. A failure analysis of the drive turbine spindle shaft was conducted in order to determine the cause of failure: whether due to a material or design flaw. Also, a dynamic analysis was conducted in order to determine the natural modes present in the system and the associated frequencies that could have contributed...

An unusual and spectacular case of spindle cell lipoma of the posterior neck invading the spinal cervical canal and posterior cranial fossa.

Science.gov (United States)

Petit, Damien; Menei, Philippe; Fournier, Henri-Dominique

2011-11-01

The authors describe the first case of spindle cell lipoma of the posterior neck invading the upper cervical spinal canal and the posterior cranial fossa. Spindle cell lipoma is an extremely rare variant of benign lipoma. It usually occurs as a solitary subcutaneous well-circumscribed lesion in the posterior neck or shoulders of adult men. Local aggressiveness is unusual. This 61-year-old man presented with an increased left cerebellar syndrome and headaches. He also had a posterior neck tumefaction, which had been known about for a long time. Computed tomography and MR imaging studies revealed a voluminous mass extending to the upper cervical canal and posterior cranial fossa and eroding the neighboring bones. The lesion was well delimited, and contrast enhancement was intense and heterogeneous. The tumor, which had initially developed under the muscles of the posterior neck, was totally resected. Histological assessment revealed numerous fat cells with spindle cells secreting collagen. The large size of the tumor and the submuscular location, bone erosion, and compression of the CNS were unusual in this rare subtype of benign adipose tumor. Its presentation could simulate a sarcoma.

Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot

Science.gov (United States)

Layne, Charles S.; Forth, Katharine E.; Abercromby, Andrew F. J.

2005-05-01

Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.

Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes.

Science.gov (United States)

Henao-Holguín, Laura Verónica; Basiuk, Vladimir A

2015-06-01

Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

DNA damage regulates alternative splicing through changes in POL II elongation

International Nuclear Information System (INIS)

Munoz, M.J.; Perez Santangelo, M.S.; De la Mata, M.; Kornblihtt, A.R.

2008-01-01

Many apoptotic genes are regulated via alternative splicing (AS) but little is known about the mechanisms controlling AS in stress situations derived from DNA damage. Here we show that ultraviolet (UV) radiation affects co-transcriptional, but not post transcriptional, AS through a systemic mechanism involving a CDK-9-dependent hyper phosphorylation of RNA polymerase II carboxy terminal domain (CTD) and a subsequent and unprecedented inhibition of transcriptional elongation, estimated in vivo and in real time by FRAP. To mimic this hyper phosphorylation we used CTD mutants with serines 2 or 5 substituted by glutamic acids and found that they not only display lower elongation rates but duplicate the effects of UV light on AS in the absence of irradiation. Consistently, substitution of the serines with alanines prevents the UV effect on splicing. These results represent the first in vivo proof of modulation of elongation in response to an environmental signal, affecting in turn the kinetic coupling between transcription and splicing. (authors)

Comprehensive Analysis of Mandibular Residual Asymmetry after Bilateral Sagittal Split Ramus Osteotomy Correction of Menton Point Deviation.

Science.gov (United States)

Lin, Han; Zhu, Ping; Lin, Qiuping; Huang, Xiaoqiong; Xu, Yue; Yang, Xiaoping

2016-01-01

Facial asymmetry often persists even after mandibular deviation corrected by the bilateral sagittal split ramus osteotomy (BSSRO) operation, since the reference facial sagittal plane for the asymmetry analysis is usually set up before the mandibular menton (Me) point correction. Our aim is to develop a predictive and quantitative method to assess the true asymmetry of the mandible after a midline correction performed by a virtual BSSRO, and to verify its availability by evaluation of the post-surgical improvement. A retrospective cohort study was conducted at the Hospital of Stomatology, Sun Yat-sen University (China) of patients with pure hemi-mandibular elongation (HE) from September 2010 through May 2014. Mandibular models were reconstructed from CBCT images of patients with pre-surgical orthodontic treatment. After mandibular de-rotation and midline alignment with virtual BSSRO, the elongation hemi-mandible was virtually mirrored along the facial sagittal plane. The residual asymmetry, defined as the superimposition and boolean operation of the mirrored elongation side on the normal side, was calculated, including the volumetric differences and the length of transversal and vertical asymmetry discrepancy. For more specific evaluation, both sides of the hemi-mandible were divided into the symphysis and parasymphysis (SP), mandibular body (MB), and mandibular angle (MA) regions. Other clinical variables include deviation of Me point, dental midline and molar relationship. The measurement of volumetric discrepancy between the two sides of post-surgical hemi-mandible were also calculated to verify the availability of virtual surgery. Paired t-tests were computed and the P value was set at .05. This study included 45 patients. The volume differences were 407.8±64.8 mm3, 2139.1±72.5 mm3, and 422.5±36.9 mm3; residual average transversal discrepancy, 1.9 mm, 1.0 mm, and 2.2 mm; average vertical discrepancy, 1.1 mm, 2.2 mm, and 2.2 mm (before virtual surgery). The

Are lesions induced by ionizing radiation direct blocks to DNA chain elongation

International Nuclear Information System (INIS)

Painter, R.B.

1983-01-01

Ionizing radiation blocks DNA chain elongation in normal diploid fibroblasts but not in fibroblasts from patients with ataxia-telangiectasia, even though there are no differences in the damage induced between the two cell types. This difference suggests that radiation-induced lesions in DNA are not themselves blocks to chain elongation in ataxia cells and raises the possibility that in normal cells a mediator exists between DNA damage and chain termination

DNA Double Strand Break Response and Limited Repair Capacity in Mouse Elongated Spermatids

Directory of Open Access Journals (Sweden)

Emad A. Ahmed

2015-12-01

Full Text Available Spermatids are extremely sensitive to genotoxic exposures since during spermiogenesis only error-prone non homologous end joining (NHEJ repair pathways are available. Hence, genomic damage may accumulate in sperm and be transmitted to the zygote. Indirect, delayed DNA fragmentation and lesions associated with apoptotic-like processes have been observed during spermatid elongation, 27 days after irradiation. The proliferating spermatogonia and early meiotic prophase cells have been suggested to retain a memory of a radiation insult leading later to this delayed fragmentation. Here, we used meiotic spread preparations to localize phosphorylate histone H2 variant (γ-H2AX foci marking DNA double strand breaks (DSBs in elongated spermatids. This technique enabled us to determine the background level of DSB foci in elongated spermatids of RAD54/RAD54B double knockout (dko mice, severe combined immunodeficiency SCID mice, and poly adenosine diphosphate (ADP-ribose polymerase 1 (PARP1 inhibitor (DPQ-treated mice to compare them with the appropriate wild type controls. The repair kinetics data and the protein expression patterns observed indicate that the conventional NHEJ repair pathway is not available for elongated spermatids to repair the programmed and the IR-induced DSBs, reflecting the limited repair capacity of these cells. However, although elongated spermatids express the proteins of the alternative NHEJ, PARP1-inhibition had no effect on the repair kinetics after IR, suggesting that DNA damage may be passed onto sperm. Finally, our genetic mutant analysis suggests that an incomplete or defective meiotic recombinational repair of Spo11-induced DSBs may lead to a carry-over of the DSB damage or induce a delayed nuclear fragmentation during the sensitive programmed chromatin remodeling occurring in elongated spermatids.

Methanol as an alternative electron donor in chain elongation for butyrate and caproate formation

NARCIS (Netherlands)

Chen, W.S.; Ye, Y.; Steinbusch, K.J.J.; Strik, D.P.B.T.B.; Buisman, C.J.N.

2016-01-01

Chain elongation is an emerging mixed culture biotechnology converting acetate into valuable biochemicals by using ethanol as an external electron donor. In this study we proposed to test another potential electron donor, methanol, in chain elongation. Methanol can be produced through the

Association between regulator of telomere elongation helicase1 (RTEL1) gene and HAPE risk

Science.gov (United States)

Rong, Hao; He, Xue; Zhu, Linhao; Zhu, Xikai; Kang, Longli; Wang, Li; He, Yongjun; Yuan, Dongya; Jin, Tianbo

2017-01-01

Abstract High altitude pulmonary edema (HAPE) is a paradigm of pulmonary edema. Mutations in regulator of telomere elongation helicase1 (RTEL1) represent an important contributor to risk for pulmonary fibrosis. However, little information is found about the association between RTEL1 and HAPE risk. The present study was undertaken to tentatively explore the potential relation between single-nucleotide polymorphisms (SNPs) in RTEL1 and HAPE risk in Chinese Han population. A total of 265 HAPE patients and 303 healthy controls were included in our case-control study. Four SNPs in RTEL1 were selected and genotyped using the Sequenom MassARRAY method. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by unconditional logistic regression with adjustment for gender and age. All P values were Bonferroni corrected, and statistical significance was set at P RTEL1 and a decreased risk HAPE in the Chinese population. The results need further confirmation. PMID:28953687

Suppression of vertical instability in elongated current-carrying plasmas by applying stellarator rotational transform

International Nuclear Information System (INIS)

ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Ma, X.; Maurer, D. A.; Pandya, M. D.; Traverso, P.

2014-01-01

The passive stability of vertically elongated current-carrying toroidal plasmas has been investigated in the Compact Toroidal Hybrid, a stellarator/tokamak hybrid device. In this experiment, the fractional transform f, defined as the ratio of the imposed external rotational transform from stellarator coils to the total rotational transform, was varied from 0.04 to 0.50, and the elongation κ was varied from 1.4 to 2.2. Plasmas that were vertically unstable were evidenced by motion of the plasma in the vertical direction. Vertical drifts are measured with a set of poloidal field pickup coils. A three chord horizontally viewing interferometer and a soft X-ray diode array confirmed the drifts. Plasmas with low fractional transform and high elongation are the most susceptible to vertical instability, consistent with analytic predictions that the vertical mode in elongated plasmas can be stabilized by the poloidal field of a relatively weak stellarator equilibrium

A spindle cell anaplastic pancreatic carcinoma with rhabdoid features following curative resection.

Science.gov (United States)

Abe, Tomoyuki; Amano, Hironobu; Hanada, Keiji; Okazaki, Akihisa; Yonehara, Shuji; Kuranishi, Fumito; Nakahara, Masahiro; Kuroda, Yoshinori; Noriyuki, Toshio

2016-08-01

Anaplastic pancreatic carcinoma (ANPC) accounts for ~5% of all pancreatic ductal adenocarcinoma cases. Due to its rarity, its clinical features and surgical outcomes remain to be clearly understood. A 74-year-old woman was admitted to Onomichi General Hospital (Onomichi, Japan) in April 2015 without any significant past medical history. Contrast-enhanced computed tomography (CT) revealed a 9.5×8.0 cm tumor in the body and tail of the pancreas. The patient developed acute abdominal pain 3 weeks later and the CT revealed massive abdominal bleeding caused by tumor rupture. The tumor increased in size and reached 12.0×10.0 cm in maximal diameter. The tumor doubling time was estimated to be 13 days. 18 F-fluorodeoxyglucose (FDG) positron emission tomography/CT confirmed the absence of distant metastasis since FDG accumulation was detected only in the tumor lesion. Emergency distal pancreatectomy and splenectomy were performed. Histologically, the tumor was classified as a spindle cell ANPC with rhabdoid features. The patient succumbed to mortality 8 months following the surgery while undergoing systemic adjuvant chemotherapy for multiple liver metastases. ANPC is difficult to detect in the early stages due to its progressive nature and atypical radiological findings. Long-term survival can be achieved only by curative resection; therefore, surgical resection must be performed whenever possible, even if the chance of long-term survival following surgery is considered dismal. As the present case suggested, spindle cell ANPC with rhabdoid features is highly aggressive and curative-intent resection must not be delayed.

The high temperature out-of-pile test of LVDT for elongation measurement of fuel pellet

Energy Technology Data Exchange (ETDEWEB)

Son, J. M.; Kim, B. K.; Jo, M. S.; Joo, K. N.; Park, S. J.; Gang, Y. H.; Kim, Y. J. [KAERI, Taejon (Korea, Republic of)

2003-10-01

As a part of the development of instrumentation technologies for the nuclear fuel irradiation test in HANARO(High-flux Advanced Nuclear Application Reactor), the elongation measurement technique of the fuel pellet is being developed using LVDT(Linear Variable Differential Transformer). The well qualified out-of-pile test were needed to understand the LVDT's detail characteristics at high temperature for the detail design of the fuel irradiation instrumented capsule, because LVDT is very sensitive to variation of temperature. Therefore, the high temperature out-of-pile test system for fuel pellet elongation was developed, and this test was performed under the temperature condition between room temperature and 300 .deg. C with increasing the elongation from 0 to 5 mm. The LVDT's high temperature characteristics and temperature sensitivity of LVDT were analyzed through this experiment. Based on the result of this test, the method for the application of LVDT and elongation detector at high temperature was introduced. It is known that the results will be used to predict accurately the elongation of fuel pellet during irradiation test.

A pollen-specific RALF from tomato that regulates pollen tube elongation.

Science.gov (United States)

Covey, Paul A; Subbaiah, Chalivendra C; Parsons, Ronald L; Pearce, Gregory; Lay, Fung T; Anderson, Marilyn A; Ryan, Clarence A; Bedinger, Patricia A

2010-06-01

Rapid Alkalinization Factors (RALFs) are plant peptides that rapidly increase the pH of plant suspension cell culture medium and inhibit root growth. A pollen-specific tomato (Solanum lycopersicum) RALF (SlPRALF) has been identified. The SlPRALF gene encodes a preproprotein that appears to be processed and released from the pollen tube as an active peptide. A synthetic SlPRALF peptide based on the putative active peptide did not affect pollen hydration or viability but inhibited the elongation of normal pollen tubes in an in vitro growth system. Inhibitory effects of SlPRALF were detectable at concentrations as low as 10 nm, and complete inhibition was observed at 1 mum peptide. At least 10-fold higher levels of alkSlPRALF, which lacks disulfide bonds, were required to see similar effects. A greater effect of peptide was observed in low-pH-buffered medium. Inhibition of pollen tube elongation was reversible if peptide was removed within 15 min of exposure. Addition of 100 nm SlPRALF to actively growing pollen tubes inhibited further elongation until tubes were 40 to 60 mum in length, after which pollen tubes became resistant to the peptide. The onset of resistance correlated with the timing of the exit of the male germ unit from the pollen grain into the tube. Thus, exogenous SlPRALF acts as a negative regulator of pollen tube elongation within a specific developmental window.

Influence of ovarian muscle contraction and oocyte growth on egg chamber elongation in Drosophila.

Science.gov (United States)

Andersen, Darcy; Horne-Badovinac, Sally

2016-04-15

Organs are formed from multiple cell types that make distinct contributions to their shape. The Drosophila egg chamber provides a tractable model to dissect such contributions during morphogenesis. Egg chambers consist of 16 germ cells (GCs) surrounded by a somatic epithelium. Initially spherical, these structures elongate as they mature. This morphogenesis is thought to occur through a 'molecular corset' mechanism, whereby structural elements within the epithelium become circumferentially organized perpendicular to the elongation axis and resist the expansive growth of the GCs to promote elongation. Whether this epithelial organization provides the hypothesized constraining force has been difficult to discern, however, and a role for GC growth has not been demonstrated. Here, we provide evidence for this mechanism by altering the contractile activity of the tubular muscle sheath that surrounds developing egg chambers. Muscle hypo-contraction indirectly reduces GC growth and shortens the egg, which demonstrates the necessity of GC growth for elongation. Conversely, muscle hyper-contraction enhances the elongation program. Although this is an abnormal function for this muscle, this observation suggests that a corset-like force from the egg chamber's exterior could promote its lengthening. These findings highlight how physical contributions from several cell types are integrated to shape an organ. © 2016. Published by The Company of Biologists Ltd.

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz; Hassager, Ole

2005-01-01

The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole (PS52K) and 103 kg/mole (PS103K), and for three bidisperse polystyrene melts. The bidisperse melts consist of PS103K or PS52K and a monodisperse...... (closed loop proportional regulator) using the laser in such a way that the stretch rate at the neck is kept constant. The rheometer has been described in more detail in (A. Bach, H.K. Rasmussen and O. Hassager, Journal of Rheology, 47 (2003) 429). PS390K show a decrease in the steady viscosity as a power......-law function of the elongational rate (A. Bach, K. Almdal, H.K. Rasmussen and O. Hassager, Macromolecules 36 (2003) 5174). PS52K and PS103K show that the steady viscosity has a maximum that is respectively 100% and 50% above 3 times the zero-shear-rate viscosity. The bidisperse melts show a significant...

Hamstring Elongation Quantified Using Ultrasonography During the Straight Leg Raise Test in Individuals With Low Back Pain.

Science.gov (United States)

Kellis, Eleftherios; Ellinoudis, Athanasios; Kofotolis, Nikolaos

2015-06-01

Although the straight leg raise (SLR) test frequently is used to assess hamstring extensibility in individuals with low back pain (LBP), evidence relating LBP, SLR, and hamstring extensibility remains unclear. The SLR measures the angle between the lifted leg and the horizontal, however, and, as such, it is not a direct measure of the elongation capacity of the hamstrings. To examine the differences in hamstring elongation (quantified via ultrasonography) and SLR score between individuals with LBP and asymptomatic controls and to determine the relationship between hamstring elongation, SLR, and functional disability scores. Cross-sectional study. University laboratory. Forty men and women with chronic LBP (mean ± SD, age 43.51 ± 3.71 years and 40 control subjects (age 45.11 ± 4.01 years) participated in this study. Passive SLR, elongation assessed via ultrasonography, and functional disability. SLR score, elongation of tendinous tissue within the semitendinosus muscle, and Oswestry Disability Index. Two-way analysis of variance tests indicated a significantly lower SLR score and a greater Oswestry score in LBP group compared with control subjects (P hamstring elongation (P > .05). Gender did not have an effect on all dependent measures (P > .05). Hamstring elongation showed a low correlation with SLR score and a minimal correlation with Oswestry score. These results indicate that the SLR score is not determined by hamstring elongation (quantified via ultrasonography). Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Methanofullerene elongated nanostructure formation for enhanced organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Reyes-Reyes, M. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)], E-mail: reyesm@cactus.iico.uaslp.mx; Lopez-Sandoval, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216. San Luis Potosi (Mexico); Arenas-Alatorre, J. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000, Mexico, D.F. (Mexico); Garibay-Alonso, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216. San Luis Potosi (Mexico); Carroll, D.L. [Center for Nanotechnology and Molecular Materials, Department of Physics. Wake Forest University, Winston-Salem NC 27109 (United States); Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)

2007-11-01

Using transmission electron microscopy (TEM) and Z-contrast imaging we have demonstrated elongated nanostructure formation of fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) within an organic host through annealing. The annealing provides an enhanced mobility of the PCBM molecules and, with good initial dispersion, allows for the formation of exaggerated grain growth within the polymer host. We have assembled these nanostructures within the regioregular conjugated polymer poly(3-hexylthiophene) (P3HT). This PCBM elongated nanostructure formation maybe responsible for the very high efficiencies observed, at very low loadings of PCBM (1:0.6, polymer to PCBM), in annealed photovoltaics. Moreover, our high resolution TEM and electron energy loss spectroscopy studies clearly show that the PCBM crystals remain crystalline and are unaffected by the 200-keV electron beam.

Methanofullerene elongated nanostructure formation for enhanced organic solar cells

International Nuclear Information System (INIS)

Reyes-Reyes, M.; Lopez-Sandoval, R.; Arenas-Alatorre, J.; Garibay-Alonso, R.; Carroll, D.L.; Lastras-Martinez, A.

2007-01-01

Using transmission electron microscopy (TEM) and Z-contrast imaging we have demonstrated elongated nanostructure formation of fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) within an organic host through annealing. The annealing provides an enhanced mobility of the PCBM molecules and, with good initial dispersion, allows for the formation of exaggerated grain growth within the polymer host. We have assembled these nanostructures within the regioregular conjugated polymer poly(3-hexylthiophene) (P3HT). This PCBM elongated nanostructure formation maybe responsible for the very high efficiencies observed, at very low loadings of PCBM (1:0.6, polymer to PCBM), in annealed photovoltaics. Moreover, our high resolution TEM and electron energy loss spectroscopy studies clearly show that the PCBM crystals remain crystalline and are unaffected by the 200-keV electron beam

Applied force and elongation in the medial rectus in esotropic patients with and without movement restriction.

Science.gov (United States)

Krieger, Fernanda; Cvintal, Tadeu; Bicas, Harley

2004-12-01

To study the different ways of expressing the force-elongation relationship in medial rectus muscles in esotropia with and without muscular restriction. Twenty-nine passive force-elongation curves were obtained without restriction (group I, n = 13) and with restriction (group II, n = 10) by means of a manual pachymeter and a digital dynamometer. In group I, the mean age was 14 years and 7 days and the mean esotropia was 53.88(Delta) while in group II the mean age was 35 years and 5 days and the mean esotropia was 60.5(Delta). Comparisons of structural muscular parameters between groups I and II were made for length (38.69 +/- 0.75 vs. 32.48 +/- 1.84 mm, p elongation relationship, whether normalized or not, followed an exponential curve. The constant c, which represents force when the elongation is zero, remained the same in all curves. In contrast, the constant b, which represents the slope of the curve, showed a significant difference between the two groups only for the curves of force-absolute elongation and tension-absolute elongation. The results imply that the constant b is better for characterizing the difference between the behavior of the medial rectus in esotropia with and without restriction. In addition, the elongation normalization showed that the contractile component is similar between the two groups and, therefore, the classical way of analysis, which does not employ normalization, is appropriate to correlate muscle properties with clinical findings.

Analysis of EEG activity during sleep - brain hemisphere symmetry of two classes of sleep spindles

Science.gov (United States)

Smolen, Magdalena M.

2009-01-01

This paper presents automatic analysis of some selected human electroencephalographic patterns during deep sleep using the Matching Pursuit (MP) algorithm. The periodicity of deep sleep EEG patterns was observed by calculating autocorrelation functions of their percentage contributions. The study confirmed the increasing trend of amplitude-weighted average frequency of sleep spindles from frontal to posterior derivations. The dominant frequencies from the left and the right brain hemisphere were strongly correlated.

Germination and root elongation bioassays in six different plant species for testing Ni contamination in soil.

Science.gov (United States)

Visioli, Giovanna; Conti, Federica D; Gardi, Ciro; Menta, Cristina

2014-04-01

In vitro short-term chronic phytotoxicity germination and root elongation test were applied to test the effects of nickel (Ni) in seed germination and root elongation in six plants species: Cucumis sativus (Cucurbitaceae), Lepidium sativum and Brassica nigra (Brassicaceae), Trifolium alexandrinum and Medicago sativa (Fabaceae), Phacelia tanacetifolia (Boraginaceae). A naturally Ni rich soil was used to compare the results obtained. Unlike root elongation, germination was not affected by Ni in any of the six species tested. EC50 values, calculated on the root elongation, showed that Ni toxicity decreases in the following order: P. tanacetifolia > B. nigra > C. sativus > L. sativum > M. sativa > T. alexandrinum. The test conducted using soil elutriate revealed a significantly lower effect in both seed germination and root elongation when compared to the results obtained using untreated soil. Conversely, the test performed on soil confirmed the high sensitivity of C. sativus, P. tanacetifolia and L. sativum to Ni.

The crystal structure of elongation factor G complexed with GDP, at 2.7 A resolution.

OpenAIRE

Czworkowski, J; Wang, J; Steitz, T A; Moore, P B

1994-01-01

Elongation factor G (EF-G) catalyzes the translocation step of protein synthesis in bacteria, and like the other bacterial elongation factor, EF-Tu--whose structure is already known--it is a member of the GTPase superfamily. We have determined the crystal structure of EF-G--GDP from Thermus thermophilus. It is an elongated molecule whose large, N-terminal domain resembles the G domain of EF-Tu, except for a 90 residue insert, which covers a surface that is involved in nucleotide exchange in E...

Short-Spindled Cell Haemangioblastoma with CD34 Expression: New Histopathological Variant or Just a Stochastic Cytological Singularity?

Directory of Open Access Journals (Sweden)

Miguel Fdo. Salazar

2016-01-01

Full Text Available Haemangioblastomas are neoplasms of uncertain histogenesis with cellular and reticular variants advocated in current lore. Herein we describe an intriguing cerebellar specimen with unusual traits including spindle cell morphology and CD34 positivity. A thirty-nine-year old man had an infratentorial tumour discovered incidentally and resected three times. In all the instances, histopathological diagnosis was haemangioblastoma; nonetheless, he had neither physical stigmata nor family history of von Hippel-Lindau disease. By histology, the lesion was composed of areas of conventional stromal cells admixed with territories populated by short-spindled cells packed in lobules, sometimes giving the appearance of gomitoli. Immunoperoxidase-coupled reactions confirmed the expression of inhibin A, neuron-specific enolase (NSE, PS100, and CD57 but also revealed focal immunolabeling for CD34, CD99, and FXIIIa. This case highlights the potential phenotypical diversity that can be found within these neoplasms. Rather than uncertain histogenesis, it may in fact reflect multiple lines of differentiation—histomimesis—prone to adopt unusual morpho- and immunophenotypes in a subset of haemangioblastomas.

Dynamic Parameter Identification of Tool-Spindle Interface Based on RCSA and Particle Swarm Optimization

Directory of Open Access Journals (Sweden)

Erhua Wang

2013-01-01

Full Text Available In order to ensure the stability of machining processes, the tool point frequency response functions (FRFs should be obtained initially. By the receptance coupling substructure analysis (RCSA, the tool point FRFs can be generated quickly for any combination of holder and tool without the need of repeated measurements. A major difficulty in the sub-structuring analysis is to determine the connection parameters at the tool-holder interface. This study proposed an identification method to recognize the connection parameters at the tool-holder interface by using RCSA and particle swarm optimization (PSO. In this paper, the XHK machining center is divided into two components, which are the tool and the spindle assembly firstly. After that, the end point FRFs of the tool are achieved by mode superposition method. The end receptances of the spindle assembly with complicated structure are obtained by impacting test method. Through translational and rotational springs and dampers, the tool point FRF of the machining center is obtained by coupling the two components. Finally, PSO is adopted to identify the connection parameters at the tool-holder interface by minimizing the difference between the predicted and the measured tool point FRFs. Comparison results between the predicted and measured tool point FRFs show a good agreement and demonstrate that the identification method is valid in the identification of connection parameters at the tool-holder interface.

Adiabatic compression of elongated field-reversed configurations

International Nuclear Information System (INIS)

Spencer, R.L.; Tuszewski, M.; Linford, R.K.

1983-01-01

The adiabatic compression of an elongated field-reversed configuration (FRC) is computed by using a one-dimensional approximation. The one-dimensional results are checked against a two-dimensional equilibrium code. For ratios of FRC separatrix length to separatrix radius greater than about ten, the one-dimensional results are accurate within 10%. To this accuracy, the adiabatic compression of FRC's can be described by simple analytic formulas

Improving the Determination of Eastern Elongations of Planetary Satellites in the Astronomical Almanac

Science.gov (United States)

Rura, Christopher; Stollberg, Mark

2018-01-01

The Astronomical Almanac is an annual publication of the US Naval Observatory (USNO) and contains a wide variety of astronomical data used by astronomers worldwide as a general reference or for planning observations. Included in this almanac are the times of greatest eastern and northern elongations of the natural satellites of the planets, accurate to 0.1 hour UT. The production code currently used to determine elongation times generates X and Y coordinates for each satellite (16 total) in 5 second intervals. This consequentially caused very large data files, and resulted in the program devoted to determining the elongation times to be computationally intensive. To make this program more efficient, we wrote a Python program to fit a cubic spline to data generated with a 6-minute time step. This resulted in elongation times that were found to agree with those determined from the 5 second data currently used in a large number of cases and was tested for 16 satellites between 2017 and 2019. The accuracy of this program is being tested for the years past 2019 and, if no problems are found, the code will be considered for production of this section of The Astronomical Almanac.

Gravimorphism in rice and barley: promotion of leaf elongation by vertical inversion in agravitropically growing plants.

Science.gov (United States)

Abe, K; Takahashi, H; Suge, H

1998-12-01

We have compared shoot responses of agravitropic rice and barley plants to vertical inversion with those of normal ones. When rice plants were vertically inverted, the main stems of a japonica type of rice, cv. Kamenoo, showed negative gravitropism at nodes 2-15 of both elongated and non-elongated internodes. However, shoots of lazy line of rice, lazy-Kamenoo, bent gravitropically at nodes 11-15 only elongated internodes but not at nodes 2-10 of non-elongated ones. Thus, shoots of Kamenoo responded gravitropically at all stages of growth, whereas shoots of lazy-Kamenoo did not show gravitropic response before heading. In Kamenoo plants, lengths of both leaf-sheath and leaf-blade were shortened by vertical inversion, but those of the vertically inverted plants of lazy-Kamenoo were significantly longer than the plants in an upright position. When agravitropic and normal plants of barley were vertically inverted, the same results as in rice were obtained; elongation of both leaf-sheath and leaf-blade was inhibited in normal barley plants, Chikurin-Ibaragi No. 1, but significantly stimulated in agravitropic plants of serpentina barley. These results suggest that vertical inversion of rice and barley plants enhances the elongation growth of leaves in the absence of tropistic response.

Effects of rare earth oxide nanoparticles on root elongation of plants.

Science.gov (United States)

Ma, Yuhui; Kuang, Linglin; He, Xiao; Bai, Wei; Ding, Yayun; Zhang, Zhiyong; Zhao, Yuliang; Chai, Zhifang

2010-01-01

The phytotoxicity of four rare earth oxide nanoparticles, nano-CeO(2), nano-La(2)O(3), nano-Gd(2)O(3) and nano-Yb(2)O(3) on seven higher plant species (radish, rape, tomato, lettuce, wheat, cabbage, and cucumber) were investigated in the present study by means of root elongation experiments. Their effects on root growth varied greatly between different nanoparticles and plant species. A suspension of 2000 mg L(-1) nano-CeO(2) had no effect on the root elongation of six plants, except lettuce. On the contrary, 2000 mg L(-1) suspensions of nano-La(2)O(3), nano-Gd(2)O(3) and nano-Yb(2)O(3) severely inhibited the root elongation of all the seven species. Inhibitory effects of nano-La(2)O(3), nano-Gd(2)O(3), and nano-Yb(2)O(3) also differed in the different growth process of plants. For wheat, the inhibition mainly took place during the seed incubation process, while lettuce and rape were inhibited on both seed soaking and incubation process. The fifty percent inhibitory concentrations (IC(50)) for rape were about 40 mg L(-1) of nano-La(2)O(3), 20mg L(-1) of nano-Gd(2)O(3), and 70 mg L(-1) of nano-Yb(2)O(3), respectively. In the concentration ranges used in this study, the RE(3+) ion released from the nanoparticles had negligible effects on the root elongation. These results are helpful in understanding phytotoxicity of rare earth oxide nanoparticles. Copyright 2009 Elsevier Ltd. All rights reserved.

Chain elongation and cyclization in type III PKS DpgA.

Science.gov (United States)

Wu, Hai-Chen; Li, Yi-San; Liu, Yu-Chen; Lyu, Syue-Yi; Wu, Chang-Jer; Li, Tsung-Lin

2012-04-16

Chain elongation and cyclization of precursors of dihydroxyphenylacetyl-CoA (DPA-CoA) catalyzed by the bacterial type III polyketide synthase DpgA were studied. Two labile intermediates, di- and tri-ketidyl-CoA (DK- and TK-CoA), were proposed and chemically synthesized. In the presence of DpgABD, each of these with [(13)C(3)]malonyl-CoA (MA-CoA) was able to form partially (13)C-enriched DPA-CoA. By NMR and MS analysis, the distribution of (13)C atoms in the partially (13)C-enriched DPA-CoA shed light on how the polyketide chain elongates and cyclizes in the DpgA-catalyzed reaction. Polyketone intermediates elongate in a manner different from that which had been believed: two molecules of DK-CoA, or one DK-CoA plus one acetoacetyl-CoA (AA-CoA), but not two molecules of AA-CoA can form one molecule of DPA-CoA. As a result, polyketidyl-CoA serves as both the starter and extender, whereas polyketone-CoA without the terminal carboxyl group can only act as an extender. The terminal carboxyl group is crucial for the cyclization that likely takes place on CoA. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Muscle spindle thixotropy affects force perception through afferent-induced facilitation of the motor pathways as revealed by the Kohnstamm effect.

Science.gov (United States)

Monjo, Florian; Forestier, Nicolas

2018-04-01

This study was designed to explore the effects of intrafusal thixotropy, a property affecting muscle spindle sensitivity, on the sense of force. For this purpose, psychophysical measurements of force perception were performed using an isometric force matching paradigm of elbow flexors consisting of matching different force magnitudes (5, 10 and 20% of subjects' maximal voluntary force). We investigated participants' capacity to match these forces after their indicator arm had undergone voluntary isometric conditioning contractions known to alter spindle thixotropy, i.e., contractions performed at long ('hold long') or short muscle lengths ('hold short'). In parallel, their reference arm was conditioned at the intermediate muscle length ('hold-test') at which the matchings were performed. The thixotropy hypothesis predicts that estimation errors should only be observed at low force levels (up to 10% of the maximal voluntary force) with overestimation of the forces produced following 'hold short' conditioning and underestimation following 'hold long' conditioning. We found the complete opposite, especially following 'hold-short' conditioning where subjects underestimated the force they generated with similar relative error magnitudes across force levels. In a second experiment, we tested the hypothesis that estimation errors depended on the degree of afferent-induced facilitation using the Kohnstamm phenomenon as a probe of motor pathway excitability. Because the stronger post-effects were observed following 'hold-short' conditioning, it appears that the conditioning-induced excitation of spindle afferents leads to force misjudgments by introducing a decoupling between the central effort and the cortical motor outputs.

Promoting chain elongation in mixed culture acidification reactors by addition of ethanol

International Nuclear Information System (INIS)

Grootscholten, T.I.M.; Kinsky dal Borgo, F.; Hamelers, H.V.M.; Buisman, C.J.N.

2013-01-01

In this research we investigate a microbial production process to produce medium chain fatty acids (MCFAs) based on the organic fraction of municipal solid waste (OFMSW). In this microbial production process, called chain elongation, bacteria produce medium chain fatty acids (MCFAs) from ethanol and volatile fatty acids (VFAs). MCFAs could be used as new biomass based building blocks for the chemical and fuel industry. The objective of this article is to investigate whether chain elongation can be promoted during acidification of OFMSW by addition of ethanol. The results show that chain elongation can be promoted during acidification of OFMSW by addition of ethanol. However, the hydrolysis rate and the carboxylic acid yield of the OFMSW in reactors with ethanol additions were lower than the hydrolysis rate and the carboxylic acid yield than in reactors without ethanol additions. Further research is required to determine whether a combined chain elongation and acidification reactor or a separated reactor system is more advantageous for MCFA production from OFMSW. -- Highlights: ► Production of medium chain fatty acids from municipal solid waste and ethanol. ► Insight in production of caproate and consumption of in-situ produced ethanol. ► Ethanol additions reduced propionate, butyrate and valerate concentrations. ► Ethanol additions hardly reduced acetate concentrations. ► Hydrolysis rate was lower in experiments with ethanol additions

Abscisic Acid Regulates Auxin Homeostasis in Rice Root Tips to Promote Root Hair Elongation

Directory of Open Access Journals (Sweden)

Tao Wang

2017-06-01

Full Text Available Abscisic acid (ABA plays an essential role in root hair elongation in plants, but the regulatory mechanism remains to be elucidated. In this study, we found that exogenous ABA can promote rice root hair elongation. Transgenic rice overexpressing SAPK10 (Stress/ABA-activated protein kinase 10 had longer root hairs; rice plants overexpressing OsABIL2 (OsABI-Like 2 had attenuated ABA signaling and shorter root hairs, suggesting that the effect of ABA on root hair elongation depends on the conserved PYR/PP2C/SnRK2 ABA signaling module. Treatment of the DR5-GUS and OsPIN-GUS lines with ABA and an auxin efflux inhibitor showed that ABA-induced root hair elongation depends on polar auxin transport. To examine the transcriptional response to ABA, we divided rice root tips into three regions: short root hair, long root hair and root tip zones; and conducted RNA-seq analysis with or without ABA treatment. Examination of genes involved in auxin transport, biosynthesis and metabolism indicated that ABA promotes auxin biosynthesis and polar auxin transport in the root tip, which may lead to auxin accumulation in the long root hair zone. Our findings shed light on how ABA regulates root hair elongation through crosstalk with auxin biosynthesis and transport to orchestrate plant development.

Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

OpenAIRE

Chon W.; Amano R. S.

2005-01-01

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a 1.1m wide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Do...

Differential expression of α-L-arabinofuranosidases during maize (Zea mays L.) root elongation.

Science.gov (United States)

Kozlova, Liudmila V; Gorshkov, Oleg V; Mokshina, Natalia E; Gorshkova, Tatyana A

2015-05-01

Specific α- l -arabinofuranosidases are involved in the realisation of elongation growth process in cells with type II cell walls. Elongation growth in a plant cell is largely based on modification of the cell wall. In type II cell walls, the Ara/Xyl ratio is known to decrease during elongation due to the partial removal of Ara residues from glucuronoarabinoxylan. We searched within the maize genome for the genes of all predicted α-L-arabinofuranosidases that may be responsible for such a process and related their expression to the activity of the enzyme and the amount of free arabinose measured in six zones of a growing maize root. Eight genes of the GH51 family (ZmaABFs) and one gene of the GH3 family (ZmaARA-I) were identified. The abundance of ZmaABF1 and 3-6 transcripts was highly correlated with the measured enzymatic activity and free arabinose content that significantly increased during elongation. The transcript abundances also coincided with the pattern of changes in the Ara/Xyl ratio of the xylanase-extractable glucuronoarabinoxylan described in previous studies. The expression of ZmaABF3, 5 and 6 was especially up-regulated during elongation although corresponding proteins are devoid of the catalytic glutamate at the proper position. ZmaABF2 transcripts were specifically enriched in the root cap and meristem. A single ZmaARA-I gene was not expressed as a whole gene but instead as splice variants that encode the C-terminal end of the protein. Changes in the ZmaARA-I transcript level were rather moderate and had no significant correlation with free arabinose content. Thus, elongation growth of cells with type II cell walls is accompanied by the up-regulation of specific and predicted α-L-arabinofuranosidase genes, and the corresponding activity is indeed pronounced and is important for the modification of glucuronoarabinoxylan, which plays a key role in the modification of the cell wall supramolecular organisation.

Towards an understanding of structure-function relationships of elongation factor Tu

DEFF Research Database (Denmark)

Wiborg, O; Andersen, C; Knudsen, Charlotte Rohde

1994-01-01

In light of the recently determined structure of elongation factor Tu, and taking into account chemical studies mapping functional sites, a number of residues have been selected for site-directed mutagenesis studies. Gly94, Gly126, His66, His118, Lys89 and Asp90 have each been point-mutated. Prel......In light of the recently determined structure of elongation factor Tu, and taking into account chemical studies mapping functional sites, a number of residues have been selected for site-directed mutagenesis studies. Gly94, Gly126, His66, His118, Lys89 and Asp90 have each been point...

Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

Energy Technology Data Exchange (ETDEWEB)

Mnasri, Najib [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Charnay, Clarence; Ménorval, Louis-Charles de [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Elaloui, Elimame [Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Zajac, Jerzy, E-mail: jerzy.zajac@umontpellier.fr [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France)

2016-11-15

Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO{sub 3} reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV–visible spectroscopy. {sup 129}Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores. - Highlights: • Mesoporous monodisperse submicron-sized silica rods were achieved. • Silver nanoparticles were located lengthwise within the intra-particle mesopores. • Textural and plasmonic properties of particles studied by {sup 129}Xe NMR and UV–Vis.

Epimerization-free C-terminal peptide activation, elongation and cyclization

NARCIS (Netherlands)

Popović, S.

2015-01-01

C-terminal peptide activation and cyclization reactions are generally accompanied with epimerization (partial loss of C‐terminal stereointegrity). Therefore, the focus of this thesis was to develop epimerization-free methods for C-terminal peptide activation to enable C-terminal peptide elongation

Adiabatic compression of elongated field-reversed configurations

Energy Technology Data Exchange (ETDEWEB)

Spencer, R.L.; Tuszewski, M.; Linford, R.K.

1983-06-01

The adiabatic compression of an elongated field-reversed configuration (FRC) is computed by using a one-dimensional approximation. The one-dimensional results are checked against a two-dimensional equilibrium code. For ratios of FRC separatrix length to separatrix radius greater than about ten, the one-dimensional results are accurate within 10%. To this accuracy, the adiabatic compression of FRC's can be described by simple analytic formulas.

The relationship between the types of axial elongation and the prevalence of lattice degeneration of the retina.

Science.gov (United States)

Yura, T

1998-02-01

To assess the relationship between the prevalence of lattice degeneration and the types of axial elongation. Nine hundred seventy eyes of 542 highly myopic patients with axial length of 26.00-31.99 mm were evaluated by using A-scan axial length measurements and fundus examinations. Then the prevalence of lattice degeneration was compared between eyes with posterior staphyloma and those without posterior staphyloma. At each axial length, lattice degeneration was more frequent in eyes without posterior staphyloma (the entire eye elongates) than those with posterior staphyloma (only the posterior pole elongates). The difference was statistically significant (plattice degeneration is influenced by the types of axial elongation in high myopic eyes.

Cessation of reproduction-related spine elongation after multiple breeding cycles in female naked mole-rats.

Science.gov (United States)

Dengler-Crish, Christine M; Catania, Kenneth C

2009-01-01

The breeding female or "queen" naked mole-rat has a uniquely elongated body morphology attributed to the lengthening of the lumbar vertebral column that occurs during pregnancy. It is unknown whether this vertebral growth is a continuous process, or associated only with early reproductive experience. We compared pregnancy-related bone elongation in nascent primiparous queens and established queens to determine if this vertebral expansion was a lifelong process in these females. We also investigated the impact of lactation on vertebral elongation in these mole-rats because it is known to be a time of significant bone loss in other mammals. Our data show that after eight or more pregnancies, established queens no longer experienced a net gain in lumbar spine length over the reproductive cycle, whereas the nascent breeders demonstrated significant spine lengthening over this time. Despite the lack of net spine lengthening in established breeders, our results indicated that these queens still experienced some pregnancy-specific vertebral elongation. In naked mole-rats, pregnancy-induced bone elongation may serve the dual purposes of first lengthening the spine, and then once optimal spine size is achieved, serving as a homeostatic mechanism that prepares the spine for the mineral demands of lactation. Anat Rec, 2009. (c) 2008 Wiley-Liss, Inc.

Species differences in ligand specificity of auxin-controlled elongation and auxin transport: comparing Zea and Vigna

Science.gov (United States)

Zhao, Hu; Hertel, Rainer; Ishikawa, Hideo; Evans, Michael L.

2002-01-01

The plant hormone auxin affects cell elongation in both roots and shoots. In roots, the predominant action of auxin is to inhibit cell elongation while in shoots auxin, at normal physiological levels, stimulates elongation. The question of whether the primary receptor for auxin is the same in roots and shoots has not been resolved. In addition to its action on cell elongation in roots and shoots, auxin is transported in a polar fashion in both organs. Although auxin transport is well characterized in both roots and shoots, there is relatively little information on the connection, if any, between auxin transport and its action on elongation. In particular, it is not clear whether the protein mediating polar auxin movement is separate from the protein mediating auxin action on cell elongation or whether these two processes might be mediated by one and the same receptor. We examined the identity of the auxin growth receptor in roots and shoots by comparing the response of roots and shoots of the grass Zea mays L. and the legume Vigna mungo L. to indole-3-acetic acid, 2-naphthoxyacetic acid, 4,6-dichloroindoleacetic acid, and 4,7-dichloroindoleacetic acid. We also studied whether or not a single protein might mediate both auxin transport and auxin action by comparing the polar transport of indole-3-acetic acid and 2-naphthoxyacetic acid through segments from Vigna hypocotyls and maize coleoptiles. For all of the assays performed (root elongation, shoot elongation, and polar transport) the action and transport of the auxin derivatives was much greater in the dicots than in the grass species. The preservation of ligand specificity between roots and shoots and the parallels in ligand specificity between auxin transport and auxin action on growth are consistent with the hypothesis that the auxin receptor is the same in roots and shoots and that this protein may mediate auxin efflux as well as auxin action in both organ types.

Characteristics of elongated and ruptured anterior cruciate ligament grafts: An analysis of 21 consecutive revision cases

Directory of Open Access Journals (Sweden)

Kohei Iio

2017-04-01

Conclusion: The location of the original femoral tunnel was more proximal in patients with elongated grafts than in those with ruptured grafts. Different bone tunnel position from native ACL might lead to graft elongation.

Barley Seed Germination/Root Elongation Toxicity Test For Evaluation Of Sludge Pre-Treatment

DEFF Research Database (Denmark)

Eriksson, Eva; Kusk, Kresten Ole; Barrett Sørensen, Mie

Application of sludge from wastewater treatment plants (WWTPs) on agricultural land is an approach for nutrient recycling that rise challenges due to recalcitrant and harmful pollutants. In this study we assessed the feasibility of a seed germination test to evaluate sludge ecotoxicity and compared...... germination responses from two test parameters, root elongation and seed germination (sprouts elongation) of the barley (Hordeum vulgare). 2nd objective was to evaluate sewage sludge pre-treatments at batch-scale of sludge samples from two WWTPs using anaerobic digestion, and thermal and ozonation pre......-treatments. Glyphosate and eco-labelled soil were used as references. Inhibition of germination of seeds exposed to the glyphosate and sludge was registered and thus germination was successfully applied for sludge ecotoxicity assessment, and using the root elongation as the end-point was both faster and more precise...

Prediction of RNA Polymerase II recruitment, elongation and stalling from histone modification data

DEFF Research Database (Denmark)

Chen, Yun; Jørgensen, Mette; Kolde, Raivo

2011-01-01

of RNAPII stalling. CONCLUSIONS: In this study we introduce a general framework to accurately predict the level of RNAPII recruitment, elongation, stalling and mRNA expression from chromatin signals. The versatility of the method also makes it ideally suited to investigate other genomic data....... strategies are needed to progress from descriptive annotation of data to quantitative, predictive models. RESULTS: Here, we describe a computational framework which with high accuracy can predict the locations of core promoters, the amount of recruited RNAPII at the promoter, the amount of elongating RNAPII...... of these four marks are found to be necessary for recruitment of RNAPII but not sufficient for the elongation. We also show that the spatial distributions of histone marks are almost as predictive as the signal strength and that a set of histone marks immediately downstream of the TSS is highly predictive...

Positive grid corrosion elongation analysis using CAE with corrosion deformation transformed into thermal phenomenon

Science.gov (United States)

Mukaitani, Ichiroh; Hayashi, Koji; Shimoura, Ichiro; Takemasa, Arihiko; Takahashi, Isamu; Tsubakino, Harushige

Valve-regulated lead-acid (VRLA) batteries have been commercially available for more than 20 years and have been enthusiastically embraced by users of uninterruptible power supplies (UPS) because of the anticipated reduction in installation and operating costs, smaller footprint and fewer environmental concerns. In Japan, communication networks are demanding reduced costs and longer life from their batteries. Among the factors limiting the life of VRLA batteries, the corrosion of positive grid material has been proven to cause elongation of the plates, loss of electrical contact and shorter lifetime. The content of Sn is also a key factor and addition of Sn in the grid alloy results in better performance in creep resistance, tensile strength and corrosion resistance [R. David Prenagaman, The Battery Man, vol. 39, September 1997, p. 16. I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. A key point is what the ratio of Sn to Ca should be, since too much Sn may lead to even worse elongation of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We have determined that microstructure control with a composition of lead-calcium-tin (Pb-Ca-Sn) alloy is optimal for better performance of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We developed a "simulation of current collector corrosion elongation" which is a technique of estimating corrosion elongation from the current collector design [I. Mukaitani, K. Hayashi, I. Shimoura, H. Takabayashi, M. Terada, A. Takemasa, I. Takahashi, K. Okamoto, Proceedings of the 44th Battery Symposium in Japan, 2003, p. 652]. Corrosion elongation occurs as the corrosion material layer grows out of the current collector metal. We resolved this problem using generally CAD

Mad2 binding to Mad1 and Cdc20, rather than oligomerization, is required for the spindle checkpoint

DEFF Research Database (Denmark)

Sironi, L; Melixetian, M; Faretta, M

2001-01-01

Mad2 is a key component of the spindle checkpoint, a device that controls the fidelity of chromosome segregation in mitosis. The ability of Mad2 to form oligomers in vitro has been correlated with its ability to block the cell cycle upon injection into Xenopus embryos. Here we show that Mad2 forms...

Brassinosteroid regulates cell elongation by modulating gibberellin metabolism in rice.

Science.gov (United States)

Tong, Hongning; Xiao, Yunhua; Liu, Dapu; Gao, Shaopei; Liu, Linchuan; Yin, Yanhai; Jin, Yun; Qian, Qian; Chu, Chengcai

2014-11-01

Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to reduced plant growth and dwarfism. However, their relationship remains unknown in rice (Oryza sativa). Here, we demonstrated that BR regulates cell elongation by modulating GA metabolism in rice. Under physiological conditions, BR promotes GA accumulation by regulating the expression of GA metabolic genes to stimulate cell elongation. BR greatly induces the expression of D18/GA3ox-2, one of the GA biosynthetic genes, leading to increased GA1 levels, the bioactive GA in rice seedlings. Consequently, both d18 and loss-of-function GA-signaling mutants have decreased BR sensitivity. When excessive active BR is applied, the hormone mostly induces GA inactivation through upregulation of the GA inactivation gene GA2ox-3 and also represses BR biosynthesis, resulting in decreased hormone levels and growth inhibition. As a feedback mechanism, GA extensively inhibits BR biosynthesis and the BR response. GA treatment decreases the enlarged leaf angles in plants with enhanced BR biosynthesis or signaling. Our results revealed a previously unknown mechanism underlying BR and GA crosstalk depending on tissues and hormone levels, which greatly advances our understanding of hormone actions in crop plants and appears much different from that in Arabidopsis thaliana. © 2014 American Society of Plant Biologists. All rights reserved.

Fatty Acid Elongation in Non-Alcoholic Steatohepatitis and Hepatocellular Carcinoma

Directory of Open Access Journals (Sweden)

Sonja M. Kessler

2014-04-01

Full Text Available Non-alcoholic steatohepatitis (NASH represents a risk factor for the development of hepatocellular carcinoma (HCC and is characterized by quantitative and qualitative changes in hepatic lipids. Since elongation of fatty acids from C16 to C18 has recently been reported to promote both hepatic lipid accumulation and inflammation we aimed to investigate whether a frequently used mouse NASH model reflects this clinically relevant feature and whether C16 to C18 elongation can be observed in HCC development. Feeding mice a methionine and choline deficient diet to model NASH not only increased total hepatic fatty acids and cholesterol, but also distinctly elevated the C18/C16 ratio, which was not changed in a model of simple steatosis (ob/ob mice. Depletion of Kupffer cells abrogated both quantitative and qualitative methionine-and-choline deficient (MCD-induced alterations in hepatic lipids. Interestingly, mimicking inflammatory events in early hepatocarcinogenesis by diethylnitrosamine-induced carcinogenesis (48 h increased hepatic lipids and the C18/C16 ratio. Analyses of human liver samples from patients with NASH or NASH-related HCC showed an elevated expression of the elongase ELOVL6, which is responsible for the elongation of C16 fatty acids. Taken together, our findings suggest a detrimental role of an altered fatty acid pattern in the progression of NASH-related liver disease.

Elongation Factor Ts Directly Facilitates the Formation and Disassembly of the Escherichia coli Elongation Factor Tu·GTP·Aminoacyl-tRNA Ternary Complex*

Science.gov (United States)

Burnett, Benjamin J.; Altman, Roger B.; Ferrao, Ryan; Alejo, Jose L.; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C.

2013-01-01

Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis. PMID:23539628

Determinants of Elongation of the Labia Minora in Tete Province ...

African Journals Online (AJOL)

AJRH Managing Editor

women may not report current vaginal ill health, it is possible that prospective cohort ... Keywords: Labia minora elongation; vaginal practices; Mozambique; survey; cross-sectional studies. ..... had ever had vaginal discharge, which was most.

Xanthium strumarium extract inhibits mammalian cell proliferation through mitotic spindle disruption mediated by xanthatin.

Science.gov (United States)

Sánchez-Lamar, Angel; Piloto-Ferrer, Janet; Fiore, Mario; Stano, Pasquale; Cozzi, Renata; Tofani, Daniela; Cundari, Enrico; Francisco, Marbelis; Romero, Aylema; González, Maria L; Degrassi, Francesca

2016-12-24

Xanthium strumarium L. is a member of the Asteraceae family popularly used with multiple therapeutic purposes. Whole extracts of this plant have shown anti-mitotic activity in vitro suggesting that some components could induce mitotic arrest in proliferating cells. Aim of the present work was to characterize the anti-mitotic properties of the X. strumarium whole extract and to isolate and purify active molecule(s). The capacity of the whole extract to inhibit mitotic progression in mammalian cultured cells was investigated to identify its anti-mitotic activity. Isolation of active component(s) was performed using a bioassay-guided multistep separation procedure in which whole extract was submitted to a progressive process of fractionation and fractions were challenged for their anti-mitotic activity. Our results show for the first time that X. strumarium whole extract inhibits assembly of the mitotic spindle and spindle-pole separation, thereby heavily affecting mitosis, impairing the metaphase to anaphase transition and inducing apoptosis. The purification procedure led to a fraction with an anti-mitotic activity comparable to that of the whole extract. Chemical analysis of this fraction showed that its major component was xanthatin. The present work shows a new activity of X. strumarium extract, i.e. the alteration of the mitotic apparatus in cultured cells that may be responsible for the anti-proliferative activity of the extract. Anti-mitotic activity is shown to be mainly exerted by xanthatin. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mapping Escherichia coli elongation factor Tu residues involved in binding of aminoacyl-tRNA

DEFF Research Database (Denmark)

Wiborg, Ove; Andersen, C; Knudsen, Charlotte Rohde

1996-01-01

Two residues of Escherichia coli elongation factor Tu involved in binding of aminoacyl-tRNA were identified and subjected to mutational analysis. Lys-89 and Asn-90 were each replaced by either Ala or Glu. The four single mutants were denoted K89A, K89E, N90A, and N90E, respectively. The mutants...... were characterized with respect to thermal and chemical stability, GTPase activity, tRNA affinity, and activity in an in vitro translation assay. Most conspicuously tRNA affinities were reduced for all mutants. The results verify our structural analysis of elongation factor Tu in complex with aminoacyl....... Their functional roles are discussed in relation to the structure of elongation factor Tu in complex with aminoacyl-tRNA. Udgivelsesdato: 1996-Aug-23...

Inhibition of CDK7 bypasses spindle assembly checkpoint via premature cyclin B degradation during oocyte meiosis.

Science.gov (United States)

Wang, HaiYang; Jo, Yu-Jin; Sun, Tian-Yi; Namgoong, Suk; Cui, Xiang-Shun; Oh, Jeong Su; Kim, Nam-Hyung

2016-12-01

To ensure accurate chromosome segregation, the spindle assembly checkpoint (SAC) delays anaphase onset by preventing the premature activation of anaphase-promoting complex/cyclosome (APC/C) until all kinetochores are attached to the spindle. Although an escape from mitosis in the presence of unsatisfied SAC has been shown in several cancer cells, it has not been reported in oocyte meiosis. Here, we show that CDK7 activity is required to prevent a bypass of SAC during meiosis I in mouse oocytes. Inhibition of CDK7 using THZ1 accelerated the first meiosis, leading to chromosome misalignment, lag of chromosomes during chromosome segregation, and a high incidence of aneuploidy. Notably, this acceleration occurred in the presence of SAC proteins including Mad2 and Bub3 at the kinetochores. However, inhibition of APC/C-mediated cyclin B degradation blocked the THZ1-induced premature polar body extrusion. Moreover, chromosomal defects mediated by THZ1 were rescued when anaphase onset was delayed. Collectively, our results show that CDK7 activity is required to prevent premature anaphase onset by suppressing the bypass of SAC, thus ensuring chromosome alignment and proper segregation. These findings reveal new roles of CDK7 in the regulation of meiosis in mammalian oocytes. Copyright © 2016 Elsevier B.V. All rights reserved.

Ardnamurchan 3D cone-sheet architecture explained by a single elongate magma chamber.

Science.gov (United States)

Burchardt, Steffi; Troll, Valentin R; Mathieu, Lucie; Emeleus, Henry C; Donaldson, Colin H

2013-10-08

The Palaeogene Ardnamurchan central igneous complex, NW Scotland, was a defining place for the development of the classic concepts of cone-sheet and ring-dyke emplacement and has thus fundamentally influenced our thinking on subvolcanic structures. We have used the available structural information on Ardnamurchan to project the underlying three-dimensional (3D) cone-sheet structure. Here we show that a single elongate magma chamber likely acted as the source of the cone-sheet swarm(s) instead of the traditionally accepted model of three successive centres. This proposal is supported by the ridge-like morphology of the Ardnamurchan volcano and is consistent with the depth and elongation of the gravity anomaly underlying the peninsula. Our model challenges the traditional model of cone-sheet emplacement at Ardnamurchan that involves successive but independent centres in favour of a more dynamical one that involves a single, but elongate and progressively evolving magma chamber system.

Transcription elongation factor GreA has functional chaperone activity.

Science.gov (United States)

Li, Kun; Jiang, Tianyi; Yu, Bo; Wang, Limin; Gao, Chao; Ma, Cuiqing; Xu, Ping; Ma, Yanhe

2012-01-01

Bacterial GreA is an indispensable factor in the RNA polymerase elongation complex. It plays multiple roles in transcriptional elongation, and may be implicated in resistance to various stresses. In this study, we show that Escherichia coli GreA inhibits aggregation of several substrate proteins under heat shock condition. GreA can also effectively promote the refolding of denatured proteins. These facts reveal that GreA has chaperone activity. Distinct from many molecular chaperones, GreA does not form stable complexes with unfolded substrates. GreA overexpression confers the host cells with enhanced resistance to heat shock and oxidative stress. Moreover, GreA expression in the greA/greB double mutant could suppress the temperature-sensitive phenotype, and dramatically alleviate the in vivo protein aggregation. The results suggest that bacterial GreA may act as chaperone in vivo. These results suggest that GreA, in addition to its function as a transcription factor, is involved in protection of cellular proteins against aggregation.

IHH and FGF8 coregulate elongation of digit primordia.

Science.gov (United States)

Zhou, Jian; Meng, Junwei; Guo, Shengzhen; Gao, Bo; Ma, Gang; Zhu, Xuming; Hu, Jianxin; Xiao, Yue; Lin, Chuwen; Wang, Hongsheng; Ding, Lusheng; Feng, Guoyin; Guo, Xizhi; He, Lin

2007-11-23

In the developing limb bud, digit pattern arises from anterior-posterior (A-P) positional information which is provided by the concentration gradient of SHH. However, the mechanisms of translating early asymmetry into morphological form are still unclear. Here, we examined the ability of IHH and FGF8 signaling to regulate digital chondrogenesis, by implanting protein-loaded beads in the interdigital space singly and in combination. We found that IHH protein induced an elongated digit and that FGF8 protein blocked the terminal phalange formation. Molecular marker analysis showed that IHH expanded Sox9 expression in mesenchymal cells possibly through up-regulated FGF8 expression. Application of both IHH and FGF8 protein induced a large terminal phalange. These results suggest that both enhanced IHH and FGF8 signaling are required for the development of additional cartilage element in limbs. IHH and FGF8 maybe play different roles and act synergistically to promote chondrogenesis during digit primordia elongation.

Initiation and elongation of lateral roots in Lactuca sativa

Science.gov (United States)

Zhang, N.; Hasenstein, K. H.

1999-01-01

Lactuca sativa cv. Baijianye seedlings do not normally produce lateral roots, but removal of the root tip or application of auxin, especially indole-butyric acid, triggered the formation of lateral roots. Primordia initiated within 9 h and were fully developed after 24 h by activating the pericycle cells opposite the xylem pole. The pericycle cells divided asymmetrically into short and long cells. The short cells divided further to form primordia. The effect of root tip removal and auxin application was reversed by 6-benzylaminopurine at concentrations >10(-8) M. The cytokinin oxidase inhibitor N1-(2chloro4pyridyl)-N2-phenylurea also suppressed auxin-induced lateral rooting. The elongation of primary roots was promoted by L-alpha-(2-aminoethoxyvinyl) glycine and silver ions, but only the latter enhanced elongation of lateral roots. The data indicate that the induction of lateral roots is controlled by basipetally moving cytokinin and acropetally moving auxin. Lateral roots appear to not produce ethylene.

Spindles and active vortices in a model of confined filament-motor mixtures.

Science.gov (United States)

Head, David A; Briels, Wj; Gompper, Gerhard

2011-11-16

Robust self-organization of subcellular structures is a key principle governing the dynamics and evolution of cellular life. In fission yeast cells undergoing division, the mitotic spindle spontaneously emerges from the interaction of microtubules, motor proteins and the confining cell walls, and asters and vortices have been observed to self-assemble in quasi-two dimensional microtubule-kinesin assays. There is no clear microscopic picture of the role of the active motors driving this pattern formation, and the relevance of continuum modeling to filament-scale structures remains uncertain. Here we present results of numerical simulations of a discrete filament-motor protein model confined to a pressurised cylindrical box. Stable spindles, nematic configurations, asters and high-density semi-asters spontaneously emerge, the latter pair having also been observed in cytosol confined within emulsion droplets. State diagrams are presented delineating each stationary state as the pressure, motor speed and motor density are varied. We further highlight a parameter regime where vortices form exhibiting collective rotation of all filaments, but have a finite life-time before contracting to a semi-aster. Quantifying the distribution of life-times suggests this contraction is a Poisson process. Equivalent systems with fixed volume exhibit persistent vortices with stochastic switching in the direction of rotation, with switching times obeying similar statistics to contraction times in pressurised systems. Furthermore, we show that increasing the detachment rate of motors from filament plus-ends can both destroy vortices and turn some asters into vortices. We have shown that discrete filament-motor protein models provide new insights into the stationary and dynamical behavior of active gels and subcellular structures, because many phenomena occur on the length-scale of single filaments. Based on our findings, we argue the need for a deeper understanding of the microscopic

Acetylcholine promotes the emergence and elongation of lateral roots of Raphanus sativus.

Science.gov (United States)

Sugiyama, Kou-ichi; Tezuka, Takafumi

2011-10-01

Radish (Raphanus sativus L.) was grown on four layers of paper towel moistened with distilled water with and without acetylcholine (ACh) for five days in the dark after sowing. ACh at 1 nM promoted the growth (emergence and elongation) of lateral roots of radish plants, but had no effect on the stems and main roots. Moreover, ACh enhanced the dry weight of roots [main (primary) + lateral roots]. Neostigmine, an inhibitor of acetylcholinesterase (AChE) also promoted the emergence and elongation of lateral roots, and atropine, a competitive inhibitor of ACh receptor, suppressed the emergence and elongation. ACh suppressed the activity of AChE and increased the amount of proteins and pyridine nucleotides (NAD and NADH) in the roots of the seedlings. It also increased the activities of NAD-forming enzymes [NAD synthetase and ATP-nicotinamide mononucleotide (ATP-NMN) adenyltransferase], and enhanced the amount of DNA in the roots of the seedlings. The relationship between ACh and the emergence and growth of lateral roots was discussed from a biochemical viewpoint.

Elongation of exogenous fatty acids by the bioluminescent bacterium Vibrio harveyi

Energy Technology Data Exchange (ETDEWEB)

Byers, D.M.

1989-01-01

Bioluminescent bacteria require myristic acid (C14:0) to produce the myristaldehyde substrate of the light-emitting luciferase reaction. Since both endogenous and exogenous C14:0 can be used for this purpose, the metabolism of exogenous fatty acids by luminescent bacteria has been investigated. Both Vibrio harveyi and Vibrio fischeri incorporated label from (1-14C)myristic acid (C14:0) into phospholipid acyl chains as well as into CO2. In contrast, Photobacterium phosphoreum did not exhibit phospholipid acylation or beta-oxidation using exogenous fatty acids. Unlike Escherichia coli, the two Vibrio species can directly elongate fatty acids such as octanoic (C8:0), lauric (C12:0), and myristic acid, as demonstrated by radio-gas liquid chromatography. The induction of bioluminescence in late exponential growth had little effect on the ability of V. harveyi to elongate fatty acids, but it did increase the amount of C14:0 relative to C16:0 labeled from (14C)C8:0. This was not observed in a dark mutant of V. harveyi that is incapable of supplying endogenous C14:0 for luminescence. Cerulenin preferentially decreased the labeling of C16:0 and of unsaturated fatty acids from all 14C-labeled fatty acid precursors as well as from (14C)acetate, suggesting that common mechanisms may be involved in elongation of fatty acids from endogenous and exogenous sources. Fatty acylation of the luminescence-related synthetase and reductase enzymes responsible for aldehyde synthesis exhibited a chain-length preference for C14:0, which also was indicated by reverse-phase thin-layer chromatography of the acyl groups attached to these enzymes. The ability of V. harveyi to activate and elongate exogenous fatty acids may be related to an adaptive requirement to metabolize intracellular C14:0 generated by the luciferase reaction during luminescence development.

Elongation of exogenous fatty acids by the bioluminescent bacterium Vibrio harveyi

International Nuclear Information System (INIS)

Byers, D.M.

1989-01-01

Bioluminescent bacteria require myristic acid (C14:0) to produce the myristaldehyde substrate of the light-emitting luciferase reaction. Since both endogenous and exogenous C14:0 can be used for this purpose, the metabolism of exogenous fatty acids by luminescent bacteria has been investigated. Both Vibrio harveyi and Vibrio fischeri incorporated label from [1-14C]myristic acid (C14:0) into phospholipid acyl chains as well as into CO2. In contrast, Photobacterium phosphoreum did not exhibit phospholipid acylation or beta-oxidation using exogenous fatty acids. Unlike Escherichia coli, the two Vibrio species can directly elongate fatty acids such as octanoic (C8:0), lauric (C12:0), and myristic acid, as demonstrated by radio-gas liquid chromatography. The induction of bioluminescence in late exponential growth had little effect on the ability of V. harveyi to elongate fatty acids, but it did increase the amount of C14:0 relative to C16:0 labeled from [14C]C8:0. This was not observed in a dark mutant of V. harveyi that is incapable of supplying endogenous C14:0 for luminescence. Cerulenin preferentially decreased the labeling of C16:0 and of unsaturated fatty acids from all 14C-labeled fatty acid precursors as well as from [14C]acetate, suggesting that common mechanisms may be involved in elongation of fatty acids from endogenous and exogenous sources. Fatty acylation of the luminescence-related synthetase and reductase enzymes responsible for aldehyde synthesis exhibited a chain-length preference for C14:0, which also was indicated by reverse-phase thin-layer chromatography of the acyl groups attached to these enzymes. The ability of V. harveyi to activate and elongate exogenous fatty acids may be related to an adaptive requirement to metabolize intracellular C14:0 generated by the luciferase reaction during luminescence development

Msd1/SSX2IP-dependent microtubule anchorage ensures spindle orientation and primary cilia formation

OpenAIRE

Hori, Akiko; Ikebe, Chiho; Tada, Masazumi; Toda, Takashi

2014-01-01

Anchoring microtubules to the centrosome is critical for cell geometry and polarity, yet the molecular mechanism remains unknown. Here we show that the conserved human Msd1/SSX2IP is required for microtubule anchoring. hMsd1/SSX2IP is delivered to the centrosome in a centriolar satellite-dependent manner and binds the microtubule-nucleator ?-tubulin complex. hMsd1/SSX2IP depletion leads to disorganised interphase microtubules and misoriented mitotic spindles with reduced length and intensity....

Lithium treatment elongates primary cilia in the mouse brain and in cultured cells

Energy Technology Data Exchange (ETDEWEB)

Miyoshi, Ko, E-mail: miyoshi@cc.okayama-u.ac.jp [Department of Brain Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Okayama 700-8558 (Japan); Kasahara, Kyosuke; Miyazaki, Ikuko; Asanuma, Masato [Department of Brain Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Okayama 700-8558 (Japan)

2009-10-30

The molecular mechanisms underlying the therapeutic effects of lithium, a first-line antimanic mood stabilizer, have not yet been fully elucidated. Treatment of the algae Chlamydomonas reinhardtii with lithium has been shown to induce elongation of their flagella, which are analogous structures to vertebrate cilia. In the mouse brain, adenylyl cyclase 3 (AC3) and certain neuropeptide receptors colocalize to the primary cilium of neuronal cells, suggesting a chemosensory function for the primary cilium in the nervous system. Here we show that lithium treatment elongates primary cilia in the mouse brain and in cultured cells. Brain sections from mice chronically fed with Li{sub 2}CO{sub 3} were subjected to immunofluorescence study. Primary cilia carrying both AC3 and the receptor for melanin-concentrating hormone (MCH) were elongated in the dorsal striatum and nucleus accumbens of lithium-fed mice, as compared to those of control animals. Moreover, lithium-treated NIH3T3 cells and cultured striatal neurons exhibited elongation of the primary cilia. The present results provide initial evidence that a psychotropic agent can affect ciliary length in the central nervous system, and furthermore suggest that lithium exerts its therapeutic effects via the upregulation of cilia-mediated MCH sensing. These findings thus contribute novel insights into the pathophysiology of bipolar mood disorder and other psychiatric diseases.

Lithium treatment elongates primary cilia in the mouse brain and in cultured cells

International Nuclear Information System (INIS)

Miyoshi, Ko; Kasahara, Kyosuke; Miyazaki, Ikuko; Asanuma, Masato

2009-01-01

The molecular mechanisms underlying the therapeutic effects of lithium, a first-line antimanic mood stabilizer, have not yet been fully elucidated. Treatment of the algae Chlamydomonas reinhardtii with lithium has been shown to induce elongation of their flagella, which are analogous structures to vertebrate cilia. In the mouse brain, adenylyl cyclase 3 (AC3) and certain neuropeptide receptors colocalize to the primary cilium of neuronal cells, suggesting a chemosensory function for the primary cilium in the nervous system. Here we show that lithium treatment elongates primary cilia in the mouse brain and in cultured cells. Brain sections from mice chronically fed with Li 2 CO 3 were subjected to immunofluorescence study. Primary cilia carrying both AC3 and the receptor for melanin-concentrating hormone (MCH) were elongated in the dorsal striatum and nucleus accumbens of lithium-fed mice, as compared to those of control animals. Moreover, lithium-treated NIH3T3 cells and cultured striatal neurons exhibited elongation of the primary cilia. The present results provide initial evidence that a psychotropic agent can affect ciliary length in the central nervous system, and furthermore suggest that lithium exerts its therapeutic effects via the upregulation of cilia-mediated MCH sensing. These findings thus contribute novel insights into the pathophysiology of bipolar mood disorder and other psychiatric diseases.

The kinesin spindle protein inhibitor filanesib enhances the activity of pomalidomide and dexamethasone in multiple myeloma

OpenAIRE

Hernández-García, Susana; San-Segundo, Laura; González-Méndez, Lorena; Corchete, Luis A; Misiewicz-Krzeminska, Irena; Martín-Sánchez, Montserrat; López-Iglesias, Ana-Alicia; Algarín, Esperanza Macarena; Mogollón, Pedro; Díaz-Tejedor, Andrea; Paíno, Teresa; Tunquist, Brian; Mateos, María-Victoria; Gutiérrez, Norma C; Díaz-Rodriguez, Elena

2017-01-01

[EN]Kinesin spindle protein inhibition is known to be an effective therapeutic approach in several malignancies. Filanesib (ARRY-520), an inhibitor of this protein, has demonstrated activity in heavily pre-treated multiple myeloma patients. The aim of the work herein was to investigate the activity of filanesib in combination with pomalidomide plus dexamethasone backbone, and the mechanisms underlying the potential synergistic effect. The ability of filanesib to enhance the activity of pomali...

The symmetric quartic map for trajectories of magnetic field lines in elongated divertor tokamak plasmas

Science.gov (United States)

Jones, Morgin; Wadi, Hasina; Ali, Halima; Punjabi, Alkesh

2009-04-01

The coordinates of the area-preserving map equations for integration of magnetic field line trajectories in divertor tokamaks can be any coordinates for which a transformation to (ψt,θ,φ) coordinates exists [A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Lett. A 364, 140 (2007)]. ψt is toroidal magnetic flux, θ is poloidal angle, and φ is toroidal angle. This freedom is exploited to construct the symmetric quartic map such that the only parameter that determines magnetic geometry is the elongation of the separatrix surface. The poloidal flux inside the separatrix, the safety factor as a function of normalized minor radius, and the magnetic perturbation from the symplectic discretization are all held constant, and only the elongation is κ varied. The width of stochastic layer, the area, and the fractal dimension of the magnetic footprint and the average radial diffusion coefficient of magnetic field lines from the stochastic layer; and how these quantities scale with κ is calculated. The symmetric quartic map gives the correct scalings which are consistent with the scalings of coordinates with κ. The effects of m =1, n =±1 internal perturbation with the amplitude that is expected to occur in tokamaks are calculated by adding a term [H. Ali, A. Punjabi, A. H. Boozer, and T. Evans, Phys. Plasmas 11, 1908 (2004)] to the symmetric quartic map. In this case, the width of stochastic layer scales as 0.35 power of κ. The area of the footprint is roughly constant. The average radial diffusion coefficient of field lines near the X-point scales linearly with κ. The low mn perturbation changes the quasisymmetric structure of the footprint, and reorganizes it into a single, large scale, asymmetric structure. The symmetric quartic map is combined with the dipole map [A. Punjabi, H. Ali, and A. H. Boozer, Phys. Plasmas 10, 3992 (2003)] to calculate the effects of magnetic perturbation from a current carrying coil. The coil position and coil current coil are

The symmetric quartic map for trajectories of magnetic field lines in elongated divertor tokamak plasmas

International Nuclear Information System (INIS)

Jones, Morgin; Wadi, Hasina; Ali, Halima; Punjabi, Alkesh

2009-01-01

The coordinates of the area-preserving map equations for integration of magnetic field line trajectories in divertor tokamaks can be any coordinates for which a transformation to (ψ t ,θ,φ) coordinates exists [A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Lett. A 364, 140 (2007)]. ψ t is toroidal magnetic flux, θ is poloidal angle, and φ is toroidal angle. This freedom is exploited to construct the symmetric quartic map such that the only parameter that determines magnetic geometry is the elongation of the separatrix surface. The poloidal flux inside the separatrix, the safety factor as a function of normalized minor radius, and the magnetic perturbation from the symplectic discretization are all held constant, and only the elongation is κ varied. The width of stochastic layer, the area, and the fractal dimension of the magnetic footprint and the average radial diffusion coefficient of magnetic field lines from the stochastic layer; and how these quantities scale with κ is calculated. The symmetric quartic map gives the correct scalings which are consistent with the scalings of coordinates with κ. The effects of m=1, n=±1 internal perturbation with the amplitude that is expected to occur in tokamaks are calculated by adding a term [H. Ali, A. Punjabi, A. H. Boozer, and T. Evans, Phys. Plasmas 11, 1908 (2004)] to the symmetric quartic map. In this case, the width of stochastic layer scales as 0.35 power of κ. The area of the footprint is roughly constant. The average radial diffusion coefficient of field lines near the X-point scales linearly with κ. The low mn perturbation changes the quasisymmetric structure of the footprint, and reorganizes it into a single, large scale, asymmetric structure. The symmetric quartic map is combined with the dipole map [A. Punjabi, H. Ali, and A. H. Boozer, Phys. Plasmas 10, 3992 (2003)] to calculate the effects of magnetic perturbation from a current carrying coil. The coil position and coil current coil are

An Elongated Leading Edge Facilitates Rotation Flap Closure: In Vivo Demonstration.

Science.gov (United States)

Lichon, Vanessa; Barbosa, Naiara; Gomez, Doug; Goldman, Glenn

2016-01-01

Variation in the design of a rotation flap may affect wound closure tension. Lengthening the leading edge of a rotation flap has been a method of reducing the tension of closure in the primary motion. An in vitro study negating this tenant has been published. The authors set out to design an in vivo experiment to determine if lengthening the leading edge of a rotation flap has the effect of reducing closure tension in the primary motion of the repair. An animal study approved by Institutional Animal Care and Use Committee was undertaken in a pig model. A tension-measuring apparatus was designed using Teflon-coated wires and digital tensiometers. Rotation flaps of a standard design and with elongated leading edges were incised on the flanks of pigs under general anesthesia. Flap closure tensions were measured at points along the leading edge of the flap and in the secondary motion. Elongating the leading edge of a flap led to a statistically significant reduction in closure tension in the primary motion of the flap and at the flap tip. The secondary motion closure tensions were essentially unaffected. The authors confirm that elongating the leading edge of a standard rotation flap will reduce closure tension in the primary flap motion.

The Prediction of Yarn Elongation of Kenyan Ring-Spun Yarn using Extreme Learning Machines (ELM

Directory of Open Access Journals (Sweden)

Josphat Igadwa Mwasiagi

2017-03-01

Full Text Available The optimization of the manufacture of cotton yarns involves several processes, while the prediction of yarn quality parameters forms an important area of investigation. This research work concentrated on the prediction of cotton yarn elongation. Cotton lint and yarn samples were collected in textile factories in Kenya.The collected samples were tested under standard testing conditions. Cotton lint parameters, machine parameters and yarn elongation were used to design yarn elongation prediction models. The elongation prediction models used three network training algorithms, including backpropagation (BP, an extreme learning machine (ELM, and a hybrid of differential evolution (DE and an ELM referred to as DE-ELM. The prediction models recorded a mean squared error (mse value of 0.001 using 11, 43 and 2 neurons in the hidden layer for the BP, ELM and DE-ELM models respectively. The ELM models exhibited faster training speeds than the BP algorithms, but required more neurons in the hidden layer than other models. The DEELM hybrid algorithm was faster than the BP algorithm, but slower than the ELM algorithm.

Sequential multisite phospho-regulation of KNL1-BUB3 interfaces at mitotic kinetochores

NARCIS (Netherlands)

Vleugel, Mathijs; Omerzu, Manja; Groenewold, Vincent; Hadders, Michael A; Lens, Susanne M A; Kops, Geert J P L

2015-01-01

Regulated recruitment of the kinase-adaptor complex BUB1/BUB3 to kinetochores is crucial for correcting faulty chromosome-spindle attachments and for spindle assembly checkpoint (SAC) signaling. BUB1/BUB3 localizes to kinetochores by binding phosphorylated MELT motifs (MELpT) in the kinetochore